Okay guys, this is my first post here, usually I'm over at the pre-powerstroke section for my IDI, but I've also owned a 1988 f-250 for several years now. It has a 351W with EFI. The truck was my daily driver for a while until something went bust and I bought my IDI and it's been setting for a while now. The truck ran fine for the longest time and one day it just lost all it's power and now I've got nothing. It starts and idles like it always did, a little choppy but nothing out of the ordinary but as it revs up it gets really choppy, pops, and backfires out the exhaust and won't maintain rpms. You can barely drive it anything over 1st gear because when you rev it up and go to shift it starts cutting out and has no power. It sparks and flames out the exhaust some like it's over-fueling or something and the manifolds get really hot and turn cherry red after it runs for a while. It has a new sender in the tank, new fuel pump, new fuel filter, new spark plugs, and plug wires, cleaned the distributor, and I'm lost... Initially I thought maybe it jumped timing, but I was told if it was any kind of timing issue it has to be extremely minute for it wouldn't start and run otherwise. I need any kind of help, ideas, or suggestions anyone may have and thanks in advance for any replies.

 

pull the codes, that will point you in the right direction. if you don't know how, google it or search it in this forum

 

Pull codes
Check fuel pressure
Check for clogged exhaust
Check timing
Do a compression and leakdown test

 

Okay guys thanks, will do. I found out how to pull the codes. I'm not in any huge hurry, I'm just working on it now as a project but without a garage it's too cold and miserable to be out fooling around with it now. Maybe this weekend I'll play around some. It hasn't been my DD for over a year now and inspection's up on it so I don't have to be in any hurry to put it back on the road. I'm actually interested in building a pulling truck out of it in the future so I'm just starting to play with it now to get a decent, running base to start from. I also remembered seeing something once out in the shed and went out tonight to take a look to see again. Just so happens my pap had a '91 and my old man had an '84 and a '90 and he had a Sunpro code scanner for all ford vehicles with the EEC-IV all the way from '81 to '95 so I have a functioning code reader for the truck and never knew it til now. If I get to check the codes this week or weekend I'll post back and let you guys know what I find out.

 

Alright guys. I just got chance to try and pull codes from the truck. I came up with a 21, a 24, a 34, and a 96. I have the book that gives the code meanings and I did not start and run the truck first because 3 of the spark plug wires got hot, and burnt and melted apart on the drivers side, I would assume from mass amount of heat off manifolds. I know the 21 and 24 have to do with coolant and air temperature because it wasn't run. The 34 say EGR valve position, does that have affect when it isn't running, and the 96 says "thermactor air system problem- right (passenger) side air flow will not bypass", but I don't know what that means or if it could cause my problem?

 

the egr code will cause running issues, but not to the extent of which you are dealing with. it needs to be addressed, but isn't your sole problem.


the air pump system can come out...so you can eliminate that from your equation. that wont solve your problem either though...


sounds like you may have a clogged cat if you are getting that much heat off of the manifolds. clogged cat = horrendous running engine with massive heat generation. I'd start there.

 

Okay so here's my question even though it isn't really a "question" per say. Like I said, it's not going to be a street truck even if I get it fixed so the cats, mufflers, and all will be coming off, so I suppose the easiest way to check this theory is just hack them off and test it out right?

 

And on top of that, like I said above, the plug wires and major heat was only on the drivers side cause the plug wires on the other bank are fine so maybe one is just in worse shape than the other? Either way I'm taking the saw to both of them plain and simple.

 

I haven't seen (or paid attention to) factory cats for quite some time...if IIRC the 351 has two cats, but both pipes feed into each. it is quite possible one side of the cat is clogged more than other, does your truck burn oil? perhaps you have some internal wear/damage to the drivers side bank that caused the cat to clog in the first place. if youre keeping the truck for a long time, it may be time to cut the cat out and planning on full exhaust.


another option is to cut the cat out so that it can be reinstalled, and if it isn't clogged you can bolt/weld it back up. if it is clogged, you can gut it and bolt it back up.

 

Well I went today and bought a new set of plug wires and threw them in, just cheapos nothing special in case they heat up and burn in trial again. Also cut the cats out of the truck and left just the downpipes from the manifolds and still isn't fixed. I had it running and you can run it up slowly and smoothly to 4500 rpm with no trouble. But as soon as you jab it, it starts spitting and sputtering and backfiring. It does the same thing like if you were to stomp on it to come from 1000 rpm up to 3000 in any kind of quickness. Slow and eased into, it'll work all day but as soon as you just jump on it it has a fit. Also still doesn't want to make any power. I drove it around some and even in 1st gear you can't get the rpms up anything past about 1150. Can run it up to 3000, let out on the clutch and it just sucks the s$#t right out of it. Back down to 900-1000 rpm

 

You have eliminated a serious computer or exhaust system problem but you still need to check fuel pressure, timing, and compression.