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89 F-150 XLT Lariat;Cam-Lope/Misfire Isues??

6K views 16 replies 8 participants last post by  Dirdy 
#1 ·
Hey guys.

Got a friend with a 89 F-150.
The thing has been running great up until about a week ago. Went outside one morning, and when he went to start it, it struggled and then promptly died. Tried several times to start again, with no change. :glum:

If he gives it some gas, itll keep running, but very roughly and with some severe misfire issues (or at least what sounds like misfire issues to me). I know he doesn't have overhead cams, but it does sound like he has cam lope. Kind of strange. :spiders:

A few details:

1. It runs smooth under throttle. But once you let off and try and let the truck coast, or while sitting at idle, it starts with the misfire issues again and acts like its going to die. :poopoo:

2. Spark plugs are only about 5 months old, it has a brand new alternator, and the battery is fairly new as well.


I had a few things I wanted to try. Mainly putting some seafoam in the tank with a full tank of 93 and seeing if that would help clean things out and help it run a little smoother (although I know this wouldn't fix the larger problem). Might also put seafoam straight into the vacuum lines.

Im figuring its either the spark plugs are already bad, his injectors have gone bad, the timing is off, thus causing the cam-lope type noise, or his computer has gone bad, thus causing the misfire as well.

Also, no check engine light or codes, which also makes me think it might be the computer, as I would think it should be putting up some kind of code with how poorly its running.

I appreciate any help yall can give, and keep the Ford jokes to a minimum please. lol :hit1:
 
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#6 · (Edited)
I am 100% confident that this is your problem:



These are notorious for this problem and not worth fixing. Unfortunately the entire vehicle has to be replaced in this situation. :biggrin:


All of the above, plus ignition module, fuel pump....really just needs to be checked out. If it has dual tanks there is a fuel lift pump on the frame rail that went bad, regulator would stick and shoot them with 80-100 lbs of fuel pressure and cause them to run really rough, and rich, or the opposite, low pressure. Some dual tank setups had it, some didnt. Newer ones had a pump in each tank instead.
 
#9 ·
haha. I was waiting for you to troll on in here (what a pun!)

The fuel pump is definitely priming. You can clearly hear it. Also, he only has one gas tank, so its not the fuel lift pump (guys over on the F-150 forums suggested the same).

They also suggested checking the sensors that Cean was talking about. Also suggested testing fuel pressure and the coil packs by moving them around. We'll probably do it on Wednesday.

I think your thinking of the DPFE,, this early of one dont have one,

usually on a ford if it wont idle,, Its the IAC stuck closed,, get it started and smack it a few times with a big wrench,, other than that is suspect low fuel pressure, some of these have a "Pony" pump in the tank, if its weak, or bad,, the frame pump wont give enough pressure and it runs like crap,
I hadn't thought of the IAC....but that definitely is something Ill check into.

Isnt it weird though that for all this rough running there isn't a single check engine code???

In any case, hes taking it (or rather I am while hes at work) to the Ford dealership to do that Motorcraft special "The Works" they're running for $29.99. Also includes his oil change. Apparently they doa full run over of the engine, but really I think hes just going to hear what Ive already told him; "Hey did you rknow you're engine was running rough? here are some possible reasons. If you want us to diagnose it, itll be another $100. Have a nice day"
 
#8 ·
I think your thinking of the DPFE,, this early of one dont have one,

usually on a ford if it wont idle,, Its the IAC stuck closed,, get it started and smack it a few times with a big wrench,, other than that is suspect low fuel pressure, some of these have a "Pony" pump in the tank, if its weak, or bad,, the frame pump wont give enough pressure and it runs like crap,
 
#10 ·
a 1989 will not have coil packs,, 1 coil,, cap, rotor wires,, blah blah,, I just thought of something,, find the fuel pressure regulator, pull the vac line off it,, and smell it,, really,, there known for leaking into the vac line,,, if you smell gas,, ahh haa
 
#14 ·
So yet another problem.

My friend's engine mounts went out last August after 400,000 miles. So he took it to get replaced.

The stupid idiot who worked on it had the engine hoisted up on metal rods that were supported by the manifolds. Well, the manifold cracked of course, and then the guy tried to say my friend had to pay for it, but thats another story.

The guy ended up replacing it twice, b/c the second one cracked on the way home.

Well yesterday it cracked AGAIN right as my friend pulled out of his house.



I told him to take to someone else, and hae the old shop that worked on it pay for it all. Im kind of hoping maybe a small crack in the manifold was the problem all along.
 
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