Fuel Pump Help

[CRZN 427]

I'm in the "first start" stage and have a possible issue with the fuel pump.

First, I had to replace my battery to get the solenoid to do it's job.

With the new battery, another Optima Red Top, I can't hear if the fuel pump is working. I believe that I should hear it make a noise as power is applied.

That leads me to think I have either a stuck or bad fuel pump, it did sit for 10+ years.

With the bad battery I was getting voltage to the contacts at the plug, I didn't check again with the new battery.

What should I check for, voltage wise, to insure I have adequate power at the plug?

Is it possible for a stuck pump, if that is my issue, to be put back in service?

What should a new pump cost?...Best source?

I'm running a stock '88 5.0 HO EFI set-up with the donor harness.

Regards, Rick.

[Doug Meldrum]

You should hear the pump run for a few seconds when you turn the key on. If your worried about it hook a voltmeter to the fuel pump to see if it gets power. Your ECU should control a relay which powers your fuel pump. Pin 22 on the ECU sends a signal to the relay. I used the relay for the fuel pump on the Ron Francis fuse panel.
You can also hook your fuel pump directly to 12v to see if it runs. If the pump runs with 12v and not when the key is turned on, trace your wiring.
I bought a BBK pump from Summit but there were several you can choose from. You need at least 50# and 200 lph. For a good pump you will pay north of $150.
Good luck.
D

[dv/dt]

Any chance your enertia switch has been tripped? When you turn on the key it should activate the EEC relay. This powers up the ECU and also provides a positive feed to the fuel pump relay's activation coil. The compute provides a negative to the fuel pump relay's activation coild and the relay sends power to the pump through the enertia switch.

You can also use a jumper wire to activate the pump. If you look at the following diagram in the top right corner you see the self test connector. If you ground the tan/light green wire (22) with the key on the pump should run (you should get 12 volts at the pump connector).

http://www.veryuseful.com/mustang/te...ng_Diagram.gif

Cheers, Rod

[AC Bill]

It could be a wiring issue. I'm not 100% sure if the clutch and/or the neutral safety switch may play a role in the pump not turning on, or not?. Do you have either?

You should hear the pump whine, but it only runs for about 3 seconds initially after the key is first turned to the run position. Listen carefully..

As suggested, first, make sure your inertia switch has not tripped. Second, check for power at the pump connector. It will take two people to do that, one to turn the key. Make sure you have a good tank harness ground connection too. You could have your test light work ok, but it is using a different ground remember..
If there is power, it's likely the pump. If not, next check to see if the relay is getting power to it, and if so, and if it's sending power through it, back to the pump. I never hear my fuel pump relay clicking, so don't rely on sound alone.

[CRZN 427]

My inertia switch is not in the "popped up" position. I'll do a continuity check to be sure. I do have a clutch switch, which needs to be tripped before the starter will engage.

I was getting voltage to the pump plug with the old battery, which should rule out the relay as a problem, I need to check voltage at the pump plug again with the new battery to see what I'm getting there, that will be first thing to day.

Then, if I don't hear the pump run, I'll try the "rubber hammer alarm clock" to see if I can "wake it up". If that doesn't do any good I'll look into a replacement pump. Of curse that means tha I'll take the old one out a tinker with it for a while first.

Thanks for the advice, I'll naturally post my findings and results.

Regards, Rick.

[rich grsc]

Why not just connect 12v directly to the pump? You will know right then if the pump runs or not.

[CRZN 427]

Originally Posted by rich grsc

Why not just connect 12v directly to the pump? You will know right then if the pump runs or not.

I checked the voltagae at pump plug to find that it isn't a full 12v, somewhere around 7-1/2 to 8. I also checked the cut-off switch and it seems to be OK, it gave me the same dull vontage reading as I got at the pump. Checking vontage to the relay gives a full 12v, that means that I'm loosing juice between the relay and the inertia switch. Possibly a bad relay?

I hooked 12v directly to the pump plug contacts and immediatelly had action. The pump came on and ran as anticipated, except being fed by the outside source it didn't shut off after a few seconds.

I did find a leak, actually two. One at the connections I put in on the steel lines, no problem as I tightened the fittings and stopped the leak.

The other was where the Mustang steel line connects to the plastic. I don't know if I can heat shrink that any tighter or if a clamp would work, doubtfull either will solve the problem. I think I will need to replace that section of fuel line. Any one have one??? It is the larger of the two near the engine, I will need about a foot of the steel line attached to the plastic from the Mustang fitting. Actually I don't remember if I made that "slip on connection as I installed the fuel lines so long ago, I have about 8" of plastic.

Next is to see if I can get the voltage issue figured out, any advice??

Regards, Rick.

[Doug Meldrum]

Next is to see if I can get the voltage issue figured out, any advice??

It sounds like a ground problem. Check that first. You would get a little resistance but not 4+v worth.

[CRZN 427]

Originally Posted by Doug Meldrum

It sounds like a ground problem. Check that first. You would get a little resistance but not 4+v worth.

I will run down the ground wire from the pump plug, if I can't do anything else I'll tap into the grouind wire close to the tank and make a ground connection there.

Regards, Rick.

[AC Bill]

Originally Posted by CRZN 427

The other was where the Mustang steel line connects to the plastic. I don't know if I can heat shrink that any tighter or if a clamp would work, doubtfull either will solve the problem. I think I will need to replace that section of fuel line. Any one have one??? It is the larger of the two near the engine, I will need about a foot of the steel line attached to the plastic from the Mustang fitting. Actually I don't remember if I made that "slip on connection as I installed the fuel lines so long ago, I have about 8" of plastic.

I gather you mean rubber, rather than plastic, as to the hose your using?

If you use the proper fuel injection rubber hosing, not just regular fuel hose, and the proper fuel injection hose clamps, not regular style hose clamps, you should be able to stop that leak.
I don't quite follow you, on wanting to replace a foot of steel line?? Ideally you should have the OEM fuel connectors in place, at the bottom of the fuel rails, and clamp the hose to where the donor flex hose needed to be cut off.
As to the other end, I used adapters and brass barbed fittings, that threaded on to my steel fuel line flare connectors. If you don't have connectors at that point, some fellows flare the end of the steel line, for a more secure connection with the rubber hose.

An idea of what I mean..


Least you know your pump is working! That will save some fooling around, and $$

[CRZN 427]

AC Bill,

My donor, an '88 GT, had Nylon fuel lines (I know I said plastic) at the place where you are showing rubber. The steel line has some ribs on the end and is pushed inside the Nylon for the seal.

If the Nylon is slightly warm it will expand and go over the end of the steel. In my case the Nylon didn't shrink back enough to seal and I have a small leak when I run the pump.

I don't remember if I cut the length of the Nylon to suit my installation, but I did cut the steel that it was originally connected to so it would fit with my istallation.

I am using a brass compression fitting to connect the piece of Mustang steel fuel line to my supplied line, with no leak there.

My Nylon lines appear to be about the same length as your rubber line so I may not have cut the Nylon to fit, but I do have a memory of inserting the steel into the Nylon, so I must have done it on one, or both, of my lines.

My latest idea is to take a Nylon spacer about 1/2" long, with an ID the same as the OD of my fuel line, cut it in half along the axis, to have two shells, and install them over the slip fit-up part of the Nylon with a hose clamp. I'm open to suggestions here as well.

I am un-able to post a picture at this time.

My computer seems to have a bug. I can't down load new programs.

I now need to install Adobe Flash Path 10 to upload pictures to PhotoBucket.

When the program finishes down loading and installing, and I select the "Finish" button, I get the Law-&-Order sound and a starement that the files can't be found. I've tried to down load form several different sources, including the Adobe site, with the same results.

In addition I can't upload any pictures to my Gallery on this Fourm either. When I try to do the upolad I get a message that the page can't be found (that is why I went back to Photobucket, I have been unable to add pictures to my Gallery on this site for well over a month). I do have a picture if I ever get rid of the bug I'll post it.

Any advice would be welcome.

Regards, Rick.

[AC Bill]

I can't help you with your Puter issues, other than doing a disc clean, and defrag. Maybe that will help clean up any errors.

Why not just use rubber fuel injection hose, and toss the nylon one? I found those OEM hoses difficult to work with, and discarded all of them.

[Doug Meldrum]

I didn't want to take a chance of a future leak so I went and had some hoses made that went from my hard line to the Ford fittings. I finally found these and had them built into the hose. It works really good. That way the hoses are custom made for your car and won't leak.



You can kinda see it in this picture.

[CRZN 427]

Doug,

Thanks for the tip, I have sent an inquiry about the fittings and I bought some brass at my loal ACE for the other end.

I found my ground connection for the pump and gauge and it didn't look as good as is should, so I moved it to a much better place. Made no difference on the voltage reading at the pump. It still won't kick in when I turn the key on.

The relay is doing something. I can hear it, and feel it, when the key is turned on. I checked the connection between the relay and the inertia switch and found it to be good.

That leaves a possibility that the inertia switch is bad, is that possible? Can it pass some current but not enough for the pump to run?

I suppose that the realy could be in that same boat, pass some current but not enough to make the pump start, but don't know how to check it out.

I'm open for any other advice on getting 12v to my pump.

Regards, Rick.

[Doug Meldrum]

Originally Posted by CRZN 427

That leaves a possibility that the inertia switch is bad, is that possible? Can it pass some current but not enough for the pump to run?

I suppose that the realy could be in that same boat, pass some current but not enough to make the pump start, but don't know how to check it out.

I'm open for any other advice on getting 12v to my pump.

Sure. Pull the plug off the inertia switch and check continuity. If your measuring resistance, that could be your problem. You could also bypass the inertia switch with a jumper and see if the pump runs or check voltage again. Just start eliminating problems until you find it.
D

[AC Bill]

So when you say you checked the connection between the relay to the inertia switch, did you just check the resistance from the pump relay to the inertia switch? Or, did you actually check to see if there was 12 volts leaving the pump relay, to the switch. The relay may still make some noise's, but perhaps it's not passing a full 12 volts.
Try jumping the switch as Doug suggested, that would be a simple test to see if it's actually the switch.

[CRZN 427]

From Doug--"Sure. Pull the plug off the inertia switch and check continuity. If your measuring resistance, that could be your problem. You could also bypass the inertia switch with a jumper and see if the pump runs or check voltage again. Just start eliminating problems until you find it."

I'll try both of those things and see what I come up with.

From AC Bill--So when you say you checked the connection between the relay to the inertia switch, did you just check the resistance from the pump relay to the inertia switch? Yes that is all I did there. Or, did you actually check to see if there was 12 volts leaving the pump relay, to the switch. I did check that as I stated in one of my previous posts, "I also checked the cut-off switch and it seems to be OK, it gave me the same dull vontage reading as I got at the pump". The relay may still make some noise's, but perhaps it's not passing a full 12 volts.
Try jumping the switch as Doug suggested, that would be a simple test to see if it's actually the switch. Yes I'll put a jumper across the terminals of the inertia switch plug and see if that makes more voltage go to the pump plug, if it does I'll also see if it is enough to activate the pump. I'll also check the resistance of the inertia switch itself.

I appreciate the advice and help. Sometimes when one is looking at at problem some of the simpelest things to try evade the thought process, like the forest and the trees thing.

Regards, Rick.

[CRZN 427]

I pulled the Inertia Switch, it didn't show any resistance when I put the meter on it so I think it is OK. I did a jumper wire at the plug and didn't get any better voltage at the Fuel Pump plug.

I pulled the Fuel Pump Relay again and don't know how to bench check it.

I did a run down of the wiring circuits.

The Inertia Switch has a two wire plug, circuits 361 and 366.
Circuit 361 (Power Relay to ECC Module) goes to: the TAB, the TAD, the MAF, the WOT A/C cut-off relay, the EGR control solenoid, All 8 injectors, and the computer.
Circuit 366 (Fuel Warning Relay Control) goes to: the Fuel Pump Relay.


The Fuel Pump Relay has four wires, circuits 366, 97, 787 and 238.
Circuit 366 (Fuel Warning Relay Control) goes to: the Inertia Switch.
Circuit 97 (Feed Back Carb Coil #3) goes to: the Computer and VIP self test plug.
Circuit 787 (Fuel Pump Safety Switch to: Fuel Pump Motor) has two wires at the connection, one goes to: the Fuel Pump Plug and the other goes to: the Computer.
Circuit 238 (Fuel Supply Pump Relay) goes to: a Fuse Link and, the Battery.


The Plug at the Fuel Pump has two wires, circuits 57 and 787.
Circuit 57 (Ground) Goes to: Chassis Ground.
Circuit 787 (Fuel Pump Safety Switch to Fuel Pump Motor) goes to: the Fuel Pump Relay.

I made a schematic, before I remembered that I still have a computer bug and can't upload pictures to my Gallery and I can't load Adobe Flash Path to put it on PhotoBucket.

I connected 12v, from the battery charger, to circuit 238 on the Fuel Pump Relay and got 12v at the Fuel Pump plug. I connected the plug to the pump, applied the 12v again and the pump came on strong.

I believe that means that I have a bad Fuel Pump Relay.

Comments welcome.

Regards, Rick.

[Doug Meldrum]

First off, have you dieted your engine harness yet? Eventually you should do this. PM me your email address and I'll send you an Excel spreadsheet showing the circuits you need to keep and the ones you need to get rid of (I made this up while dieting my 88 GT and yes it's a PITA).

What main wiring harness are you using? Ron Francis or donor?
How did you connect the two harnesses together?

The best and fastest way to test a relay is, find your horn relay - honk your horn, if it makes a honk its a good relay. Then put your fuel pump relay in the horn relay slot and honk the horn again. If it honks then its a good relay.

If your fuel pump relay is good trace the power side of your relay power (not your ECM power) back to the battery and find where your voltage drop is at. Make sure your tracing all your ground connections as well. I still think that is where your problem is at. Let us know when you have done this step, oh, and refer to Rod's schematic in post #3 when you do this. improvise if using Ron Francis's harness because you may have a bad connection somewhere. Possibly even at the Starter solenoid.

I just had an odd thought... You may have a problem in how you have the relay wired to the solenoid. check the relay first then we can explore that scenario...

[CRZN 427]

[QUOTE=Doug Meldrum;2693372]First off, have you dieted your engine harness yet?No, I am using my un-dieted '88 harness. Eventually you should do this. PM me your email address and I'll send you an Excel spreadsheet showing the circuits you need to keep and the ones you need to get rid of (I made this up while dieting my 88 GT and yes it's a PITA).

What main wiring harness are you using? Ron Francis or donor? DonorHow did you connect the two harnesses together? No Connection

The best and fastest way to test a relay is, find your horn relay - honk your horn, if it makes a honk its a good relay. Then put your fuel pump relay in the horn relay slot and honk the horn again. If it honks then its a good relay. I'll see if I can do that, I don't have my horns installed yet, I may be able to do that on the bench.

If your fuel pump relay is good trace the power side of your relay power (not your ECM power) back to the battery and find where your voltage drop is at. Make sure your tracing all your ground connections as well. I have looked and only found one ground wire in that part of the harness, I'll keep looking for more. I still think that is where your problem is at. Let us know when you have done this step, oh, and refer to Rod's schematic in post #3 when you do this. improvise if using Ron Francis's harness because you may have a bad connection somewhere. Possibly even at the Starter solenoid. After I put in my new battery I can spin the engine with no difficulty, I need to get the fuel there to get it to start.

I just had an odd thought... You may have a problem in how you have the relay wired to the solenoid. check the relay first then we can explore that scenario...I had to install a mini starter due to my headers, I followed the instructions that came with it, which is the same as I found on the Forum, and, as I stated, the starter works OK.

I'm still checking all the wiring connections, but I think the relay is the prime suspect for now. There is a plug near the fuel tank that has dielectric compound on the pins so I don't suspect a problem there.

Thanks for the help, and I'll surely post what I finally find as the problem with my low voltage at the pump.

Regards, Rick.

[rich grsc]

If you think its the relay then just buy a new one and try it. The dont cost much at all, 8-9 bucks.

[CRZN 427]

After a day of grandkid sitting I did get a few minutes in the garage.

As it turns out I have another realy that will fit. I got a bag of them from a fellow member a while back. One of them, for the Convertible Top Lift, is the same as the Fuel Pump Relay, I could even read the numbers on both.

I put it in and it didn't make any difference, I'm still getting about 6v to the pump plug. I connected a wire from the known ground in the trunk all the way to the battery ground post and still only get 6v at the plug. I can feel and hear the relay doing something when I turn the key on, same as the old ralay.

I tried connecting 12v to the power input terminal on the relay (both of them actually) but with no load except the multi meter I couldn't get any readings on any of the other terminals.

I traced each ground wire, on my Ford '88 Mustang Wiring Diagram, from the fuel pump to the only ground connection shown (the one I refer to above) and to all other devices that tie into that section of ground circuits and found no other chassis ground shown on the diagrams. I traced the wire loom on the chassis and found no ground wires on that harness and none that aren't connected to a substantial ground location, with the paint removed for contact.

My nest thing is to take our the plug that Ford put in for the Fuel Pump and Fuel Gauge, that is near the Fuel Pump in the harness, and direct solder the four wires there.

As always, comments welcome.

Regards, Rick.

[CRZN 427]

I took the 4-prong plug out of the harness and crimped & soldered all four wires for the Fuel Pump and Fuel Gauge in the trunk area.

Checked the voltage at the Pump Plug again, no change, I'm still getting about 6v there, whether I ground the meter to the wire in the plug or to the chassis.

I had more than one extra relay from the deal I made earlier and tried the others, still no difference in voltage.

I double checked the voltage coming to the Fuel Pump Relay and it is a good 12v.

I'm still open to suggestions as to why I am not getting adequate power from the relay to the pump.

Regards, Rick.

[rich grsc]

Put an ohm meter on the wire from the relay to the pump. If you have 12v at the relay and less at the pump then you must have resistance in that wire.

[CRZN 427]

Originally Posted by rich grsc

Put an ohm meter on the wire from the relay to the pump. If you have 12v at the relay and less at the pump then you must have resistance in that wire.

I'm trying to approach this problem with patience and logic, luckily, so far I still have some of each left to work with. I did do the Ohm Meter and all I got so far is that there is continuity in the circuit.

I am physically chacing down the five wires in the Fuel Pump Realy Plug.

There are three that go towards the front of the car, and through a 12 pin (2 rows of 6) flat plug. Since I'm getting 12v at the plug, they may be OK.

There are two that go to the rear, to the Inertia Switch and the Fuel Pump. I'm working on those for now to see if there is any damage inside the looms, or anywhere else. A lot of digging in and around all the installed parts and pieces.

Regards, Rick.

[CRZN 427]

I checked the continuity from the Fuel Pump Relay Plug (FPR) to the Fuel Pump Motor Plug (FPM) and to the Inertia Switch Plug (ISP).

When I check the continuity from the FPR, on the appropriate pin, to the ISP, I get a strong reading. When I check from the ISP to the other pins in the FPR I get no reading. When I check for continuituy between the ISP and GND (Ground) I get no reading. That tells me that I have a good circuit there.

When I check the continuity from the FPR to FPM I get a strong readng. When I check for continuity between the FPM and the other pins in the FPR I get some readings, of various strength on a couple of them. When I check for continuity between the FPM and GND, I also got a reading.

I checked the circuit diagrams from the FPR again. Several of them go through a device that goes to the computer, and possibly ground from there.

THe wire from the FPR to the FPM is circuit 787. That circuit has two leads off the FPR, with the other going to the Computer. I think this circuit is where I'm getting the odd readings at the other pins when checking back from the FPM.

I cut the 787 wire between the FPR and the FPM and checked the continuity for each side of the cut.

Checking from the FPM to the cut, by the FPR, I get a strong reading. When I check to ground from the FPM now I get no reading.

When I check from the FPM to the other side of the cut, going back through the FPR, I get no readings, and none at the other pins in the FPR.

I re-connected the 787 circuit and came in for the evening to ponder the data, post my findings and watch a little more Olympics.

I don't think I have any circuit faults from the readings taken at the cut wire.

Can someone check the voltage at the FPM on a running car to see if it is 12v. If not, I may still have a weak pump. If It is I still have a mystery.

As usual, any help and advice is welcome.

Reagards, Rick.

[Doug Meldrum]

The self test connector in the engine harness has a direct wire to the fuel pump. Find the connector (it's a diamond shaped plug that doesn't connect to anything) and apply power to the tan/lt green wire. The pump should run. It bypasses the relay and it will also tell you how much voltage is going to the pump. Look at the schematic in my last post. You'll see it. Work out from there and start eliminating possible problems.

By the way, 11.9v at the pump but I'm using a Ron Francis harness with a donor motor harness.

[CRZN 427]

Originally Posted by Doug Meldrum

The self test connector in the engine harness has a direct wire to the fuel pump. Find the connector (it's a diamond shaped plug that doesn't connect to anything) and apply power to the tan/lt green wire. The pump should run. It bypasses the relay and it will also tell you how much voltage is going to the pump. Look at the schematic in my last post. You'll see it. Work out from there and start eliminating possible problems.

By the way, 11.9v at the pump but I'm using a Ron Francis harness with a donor motor harness.

Doug,

Thanks for testing the voltage at the Fuel Pump Plug. It shows that I still have some research to do to solve my problem.

I've seen the self test plug on my schematics. It shows that the connection is to one of the pins in the Fuel Pump Relay Plug, through Circuit 97, the circuit from the FPR to the computer. I'll give your suggestion a try and see what happens.

I've got to get the bug out of my computer so I can post pictures again. My sketch of the circuits involved in this discussion may help us communicate a little better.


I have some coordination information between my (the Ford Schematics) circuits and the ones shown in the diagram you posted.
Ford Circuit 366 = your Circuit 37/57
Ford Circuit 238 = your Circuit 1
Ford Circuit 787 = your Circuit 19
Ford Circuit 97 = your Circuit 22


Thanks for the assistance, I can use all I can get.

Regards, Rick.

[5.8Cobra]

Is your distributor plugged in? I seem to remember the TFI having something to do with the fuel pump. Maybe you have a bad TFI module. Check for spark to verify. Just a thought..

Mike

[dv/dt]

DO NOT CONNECT POWER TO THE TAN/LT GREEN WIRE!!!!
The tan/lt green wire provides the ground to the relay not the power. If you hook power to it with the computer hooked to the harness there is every chance you will fry the computer.

Cheers, Rod

Originally Posted by Doug Meldrum

The self test connector in the engine harness has a direct wire to the fuel pump. Find the connector (it's a diamond shaped plug that doesn't connect to anything) and apply power to the tan/lt green wire. The pump should run. It bypasses the relay and it will also tell you how much voltage is going to the pump. Look at the schematic in my last post. You'll see it. Work out from there and start eliminating possible problems.

By the way, 11.9v at the pump but I'm using a Ron Francis harness with a donor motor harness.