JBronco
New member
Hey guys I have an 88 351 bronco and I have a brain wracking problem. I have posted a few other times about this poblem and have done almost everything anyone could think of so if you already helped me thank you, I am just looking for any last resorts. So here is the deal about 7 months ago I went to get in my truck to go to work and it wouldnt start. Prior to then it was running ok with no major problems, only thing that may be something to consider is it would sometimes when i was gunning it have a weird almost puffing sound comming out of what i think to have been the tail pipe. I got it towed to the shop and they got it to start by moving the distributor but even then it was still hard to start it would just keep turing over and over strong. The guys at the shop replaced the spark plugs for me and told me it had a slight miss, they also gave me a list of things that could be cause the hard start and idle issue. They told me I probobally had rust in my fuel tank as it is old and had a very small leak and that particles could have gotten in my fuel system. While it was there they did a fuel pressure test also and it came back ok 35 PSI I beleive> I decided to drive the truck home to do the repairs myself. So I got a new fuel tank,a intank fuel pump, fuel filter and, new injectors. So after two weeks i put all those things in and they didint change anything exept now it seemed the truck would sometimes dieout during the rough idle but once it had been already running it would always start right back up vise the hard start. So I talked to a friend that told me he had similar problem and it was his Cat converter. So i put a new cat on it as well as changed the EGR valve because i found it was completley clogged with carbon and seized up, again no change. So next I drove my truck to work where there is a certified mechanic that I work with to get his advise. He thought that it maybe because it had the slight miss that it could be cause the other issues. So we did a compression test and found my #7 cylinder only had 65PSI. After doing a smoke test we found the compression was leaking from the exhaust valve. He was convinced this was my problem. Over the next 3 weeks we tore my engine apart and found that infact the #7 exhast valve was a little warped so we replaced it and cleaned my heads up real good. While putting it back together we noticed that one of my lifters was sunken into the block so when I pulled it out i saw that it and only that one was wore way down it was a quarter inch shorther than the others and you could see it was being abnormally wore. Next we pulled out the cam shaft and found that lobe where the lifter was had been completley worn off and there was no lobe left. I then got new cam and lifters and put everything back together. Sure enough the truck started up easy then went right back into its up and down idle. The next day the truck was once again hard to start also so it really did nothing to help my problem at hand. I also replaced the disributor cap and rotor while reassembling just incase. So after a few weeks of being to mad to think about it I finally did some research and got a few new ideas first was the TPS, I replaced it and it did nothing. Next I replaced the IAC valve, it also did nothing. All that being said i will go ahead and say a few other things i have tried. I checked the spark on all the wires and the coil, spraved my vacuume lines with choke cleaner to check for vacuume leaks (i have a few of the tiny vaccume lines that are broken I beleive its the little yellow one and the little pink one but they were broken long before this problem), I set and reset timming several times. A few things that are note worthy are the truck is only hard to start if if has been sitting longer than an hour or so, it starts right back up if u can get it started initally. Also sometimes i can smell fuel when im trying to start it but I never see any leaking. The truck has very good throttle response and if u actually take it on the road it is fine until u come to a stop sign, then it shuts off most the time unless you keep giving it gas. And the most mind blowing thing of all and what i cannot explain nor can anyone i have talk to is that sometimes once it starts it will idle and run just like a brand new vehicle now sometimes it will stay like that for 10 mins before going back into its irratic idle others it only lasts 30 seconds, and then other times it has irratic idle immidietly. It literaly seems like everytime i get the truck to start it is a completly differnt vehicle. I cant understand how the truck is capable of running like brand new but only for a little amount of time. I know i prolly just set a record on longest post but i really wanted to get all the info out there becuase this truck is baffling all the best mechanics in the area. Any help is always appriciated Thanks.
>- You certainly have had your share of problems with that engine. Were you ever tempted to replace the whole thing? With all you have done, I'll bet you could have paid for a new one. Any way, I may have missed it but did you ever replace the pick up coil inside the distributor? When they fail, it is usually intermittent for a while and usually fail as the engine warms up. Beyond that I think I'd be looking for a new engine.
