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Discussion Starter · #1 ·
would this rule out the fuel pump or relay as a cause? it just cuts out for a split second, then comes back on (eventually it dies completely and cranks but wont restart for a while)

how does the tach get its signal?

im thinking because obviously the engine doesnt stop turning, maybe the pickup in the distributor is not getting the signal, so the tach dies?

(ive already tried replacing the coil and TFI).

91 EFI 302. 22K miles on car. thanks!

-james
 

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Road Rebel may be right. If it were a loose connection, youd expect it to happen on a bump, a curve, or some predictable physical happening.

BUT, a MSD box slowly heating up and eventually breaking down could do just what you are describing. AND, it could do this for a while before it totally craps out on you. And after cooling down it could come back.

Have you got it mounted in a cool dry place??

earl
 

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Discussion Starter · #4 ·
i dont have any MSD stuff on my car, just the stock coil and distributor. (is the MSD just a different kind of coil?)

does my tach symptom rule out a fuel problem? i.e if the engine is turning and has spark, but no fuel, will the tach show 0 or the engine speed? (the engine is turning because it is in gear and the momentum of the car keeps the engine turning)

-james

[ August 04, 2002, 02:48 PM: Message edited by: Ophitoxaemia ]
 

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The tach gets it's signal from the negative side of the two wire plug on the coil. If the tach quits, it sounds like you are losing the spark. If the fuel pump is cutting out, I would think that the engine would start to run rough for a second or two, as the fuel pressure in the line bleeds down, before quitting
 

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I had something that sounds a lot like that going on with my old truck years ago and it ended up being the coil. Their fairly cheap if your running a stock unit and it might be worth a try.
 

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If the tach is dropping out, when the engine dies, then typically either the TFI or hall sender is bad. You should get a code for PIP failure, or something like that.
Unfortunately both are heat sensitive. The hall sender has more of a progressive failure, based on the temperature, since the magnetic strength diminishes the higher the temp.
 

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sounds like a bad pick up coil to me. sometimes you get symptoms like that when the vac. advance
moves the breaker plate and the small wires from the pick up are old and worn. the car dies,no vacuum,advance releases, car will start again.try
disconecting the vac. hose to the advance and see
if it makes a difference. good luck, chris
 

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If you are going to replace the TFI do yourself a favor and spring for a good one(Ford or at the very least NAPA)I had to buy three el cheapos before buying a Ford part to fix my ingition problem.It drove me nuts.Before you do that though,if you have a Auto Zone near you go there and pick up a coil,if that dosent help you can bring it back.They take back ignition components just make sure it is resellable(clean and the package in good shape).I believe Napa tests TFI's.It's been awhile since I've read anything about testing TFI's but if I remember right it usually says something to the effect of these tests arent 100% fool proof.If that dosent solve the problem its time to pull the distributor and replace the PIP I dont think they are too much $$$.
 

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Speaking of tach's and ingitions
The night before firing my engine for the first time during the build,I couldnt resist firing it up just for a second,and fire up it did and I shut it right down.Then I though about it for a little bit and realized I didnt have my dash in therefore no oil pressure ,water temp,nothing.I carefully connect the gauges install the dash and call it a night.I go out in the morning twist the key it cranks but no fire in the hole.I check the normal stuff all seem well,but still no fire in the hole.Start checking ignition components and all seemed fine.Start changing all the ingition components one at a time(PIP,TFI,coil,cap rotor,EEC,even the dash wiring I did late the night before after starting the engine,I simply checked everything...I thought)No change,finally I decide to check the dwell,found it to be 50% :eek: way to high but still dont no why.Well to make a already too long story shorter.I get pi$$ed rip the dash out and it fires up,reconnect the tach(the only part in the ingnition not replaced)no start.I cant explain why a screwed up curcuit board it the stock tach increased the dwell that much,but there is a Autometer in there now with no more problem. :confused:

Ps I normally dont tell this story,it is kinda unblieveable.
 

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Discussion Starter · #12 ·
dont know... i changed a whole load of crap (computer, disty, computer relay)... ran perfect at the autocross yesterday. the ground wire to the computer didnt look so hot so i improved the contact to the frame.

but, gotta drive on the freeway for 1 hour to make it happen, ugh... (there's traffic around all the time so its kinda of dicey stopping most places)

-james
 
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