I've been fighting this problem for almost 1&1/2 years now. It's time to either fix it or rip out the computer controlled components and go carb'ed.

I have a 1988 F150 4x4, originally had a 302, 5spd Mazda tranny. I pulled all of that out, bought a donor truck, 1989 F250, 2WD with a 351W and ZF 5spd tranny.

THE ENGINE WILL START, REV TO ABOUT 2500 RPM AND DIE. Will not restart until I either wait about an hour or remove the spark plugs, spin it over a few times, reinstall plugs. After it starts and dies, back to the beginning.

Rebuilt the 351W, oversized pistons to .030 to clean up rust in walls. Everything else was good. Engine only had a total of 89,000 miles. Installed new pistons, rings, bearings and computer friendly camshaft from CompCams. Reassembled engine with all new seals and gaskets, engine mounts and installed engine with donor computer and engine compartment harness and all sensors.

I've replaced the TPS sensor, new throttle cable, TFI module, pick-up in distributor, new rotor, plugs and wires. The coil tested good in comparison with a new one and the one from the 302 and it puts out a 2 inch long blue spark and it "hurts". I've checked the timing at least 3 times, threw it out 180, rearranged the firing order to make sure it wasn't a 302 style and threw it out 180 again. I put a timing light on and watched it as I cranked the engine and it fired continuously even while shooting starting fluid in the TB and a "NO START".

I've swapped computers, the 302 was operating fine except for 180,000 miles, low oil pressure and a knock. Buzzed the whole harness and sensors for proper readings. No errors from computer on the KOEO tests. I get code 11.

I get 40psi at the fuel rail static and it drops to 35psi while cranking and holds this even after a no start.

I've tried plugging the TB to make sure I didn't have a massive air leak. No change other than engine wouldn't even start. I tried with exhaust disconnected at heads to make sure no restrictions, no change. I pulled the engine out, tore it apart, looked it over, found nothing obvious, reassembled and same thing happens. This means I checked the timing gears at least twice(lol).

New battery, starter, starter relay, alternator, fuel pump relay, overhauled injectors.

It would take me a $1000 to convert this thing to carb which I don't want to do so I'm offering 1/2 of that to anyone who can help me. This is not a JOKE. I offered this to a few local shops and when I told them that I would deduct the price of any part that they put on the truck that didn't fix it, they backed out of the offer. I can throw parts at it cheaper myself.

So if you have any ideas and they work, heres your chance to make some easy $$$. If you post a suggestion that I have already tried, I'll let you know. Like I said, I've been messing with this for a while and I've tried just about everything.


Thanks to all who try,
LoosMaster

P.S. To the Moderator- If this thread is not appropriate, please delete it and I'll try something else.

 

Interesting that removing the sparkplugs and putting them back in is making a difference... Are your lifters operating correctly to allow exhaust gases to exit the combustion chamber? May have something to do with that cam that you put in... Maybe removing the plugs and cranking the engine is relieving pressure... Is this truck speed density or mass air flow?

 

It is SD. That is the 3rd camshaft I tried. 1st was the original, then a high-torque performance, which I found out later was not computer compatible, then the CompCam one. All had the same symptom. Also has new lifters that came with the latest cam. I don't have any pressure release when I remove the plugs but it does take about 4-5 full spins on the engine to get it to spin over easy with the plugs out.

After the "No Start" the cranking speed slows down dramatically. After the 3rd attempt, the starter can no longer turn over the engine and I have to remove the plugs.

P.S- The compression is about 70-80psi. No break-in time.

 

Generally speaking you don't want to do any heavy engine modifications that might play with your fuel/air mixture too much without changing the system over to MAF. Not to insult your intelligence, but do you the difference between the two systems?

 

Yes, have had both systems at one time. Like I said the CompCam camshaft is a computer friendly cam for the SD system. It has a little more duration and lift than the stock but the symptom has no change even with the original factory cam installed.

 

Fair enough...

Is your oil pump working properly and properly lubricating the cylinders?

 

New oil pump. At the time it does run, indicates about 60-70psi or at the M on Normal in guage. The dragging of the engine I am relating to would be fuel wash-out of the cylinders. Each time I turn the key, the system pressurizes, cranks, dumps fuel with a no start. I would think after a few attempts of this, I'm just washing out the lube in the cylinders.

 

Yeah that seems logical... How about the ICM or ignition coil, are those new or old parts?

EDIT: In your first post you said the truck starts and revvs up to 2500rpm and then dies, but your subsequent posts indicate that it NEVER starts, just cranks. Which one is it?

 

Everything on the dizzy is new. The coil is not, swapped it with the 302 one, no change, even had both tested(good) and it throws a nice blue spark, at the coil, plug wire and at the plugs itself.

It will not start again until I remove the plugs, spin it over a few times, reinstall the plugs and crank it. It starts immediately, then dies with a "No Start" again until I go thru the procedure again. But if I let it sit for about an hour without pulling the plugs, it will Start and then die. This is the only consistent symptom.

 

I'm at a total loss... That is pretty strange... Have you vacuum tested the system?

 

Are the plugs wet when they pull them out. Does the oil smell like fuel

 

Will it stay running any longer if you give it some throttle or kill it faster? Are the throttle plates and IAC operating correctly?

 

I think what you need to do is take skandocious' truck (351 MAF rig) and use it as a parts donor. Take the computer, harness, MAF set up anything else that may be suspect and put it on your truck. While you are at it, put that taurus fan on. But, wait till next week to do this bacuse by then it will have headers on it...take those too.

 

Hahah you wish someone would dismantle my tuck eco

But I do think that is a good suggestion swapping to MAF, especially if you wanna get some performance out of this truck...

 

Sounds like the only performance he's worrying about is for it to pull its own weight...