What's new
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.

why does it do this?

az ranger

az ranger

1/2 ton status
Joined
May 9, 2004
Posts
139
Reaction score
0
Location
Safford AZ
88 jimmy 350TBI.
I don't usually drive it long distances but everytime I do lately it has problems. If I drive it over 50-75 miles especially it there is any uphill grade it dies. If I am going up a long grade it will run great until I get to the top and let off the throttle for a few seconds. As soon as I let off the throttle the engine dies and acts like it is not getting fuel. If there is no uphill grade I can drive it much longer before it happens. Also if it does die at the top of the hill I can coast down the hill especially if I coast for over a mile or more it will start up and run fine until I get to the next long hill. If I am not able to coast I pull off the road and wait about two minuets and it will start right up and go, but I have to stay constant in the throttle if I let off it usually dies again. It will always start again after waiting a couple of mins. If I don't wait and just try to start it It just cranks but wont fire up.

It does show code 32. But I have had that code for the last five years and this problem is new. Could still be an EGR problem I suppose. Would the EGR prevent it from getting fuel?

Maybe it is vapor locking?

Maybe fuel pump problems?

Anybody have input? I would appreciate it.
Thanks
Scott
 
If it were me, I'd replicate the dying condition with someone in the truck with me, immediately pull over as soon as it dies, pop the hood, and watch the injectors as someone cranks the engine.

If there is NO fuel, I'd then check spark. If there is a weak fuel pattern (has to have spark to have fuel), I'd suspect the fuel pump.
 
Probably not vacuum related since there are no other issues.

Bad gas or water in the gas should be fairly consistent as well, water is heavier than fuel, so it should be picking it up all the time if so. The "sock" at the bottom of the tank is a water barrier FWIW.

Sounds like something electrical is getting hot, and working incorrectly as the heat builds up.
 
Check the injector pattern when it dies and won't start. If there's no injector spray at all, it's almost certainly ignition related. :)
 
So if there is no fuel it would be ignition related and not a fuel pump problem. Can you educate me on this. Does the fuel pump not have power if there is an ignition problem?

Thanks for the replies.
 
Injectors are not fired until the ECM "sees" the engine turning over via the spark signal from the distributor. So if there is no spark (or the ECM thinks there isn't) then no fuel.

*Most* fuel pumps seem to fail in a less than spectacular way, many can't keep adequate pressure instead of failing outright.
 
dyeager535 said:
Check the injector pattern when it dies and won't start. If there's no injector spray at all, it's almost certainly ignition related. :)
Click to expand...

So if there is a good spray then it would also would be an ignition problem right? (although there should not be fuel with out spark)
and
If there is no fuel spray I should check the ignition coil first and then move on to the fuel pump? Sorry for the elementry questions.
 
If there is fuel, and it won't even attempt to run, theres no spark. :)

If no fuel, pull a plug wire and see if it arcs to ground while cranking. Stick a screwdriver or something metal in where the plug goes into the boot, so you can see it arc.

You are correct...without spark there should be no fuel.

The injectors get a constant 12V when the key is in run/start, the ECM grounds the other wire on the injector to fire it.
 
Ones a comment on the basics of internal combustion...without spark and fuel, an engine won't run.

Specifically for GM OBD1 injection...TBI, TPI, you have to have spark to inject the fuel. For instance, you may have fuel at the throttle body (IE the fuel pump works, which is what I meant by "has fuel") but it's not getting into the cylinders because the injectors aren't firing, based on lack of spark signal to the ECM. So the engine would be lacking fuel, but not because of the fuel delivery system, because of the ignition.

This is why its so important when one of these trucks doesn't start or run to know if the injectors are pulsing. JUST testing for injector pulse can point you towards fuel system or ignition. Injectors pulse and no fuel=fuel system problem. Injectors don't pulse=ignition problem.

Any clearer? :)
 
Yes, crystal. Thanks and that's a good bit of knowledge to shove back in my head. Can he use a stethoscope on the tbi,tpi injectors to listen for them clicking away as the engine turns over?

One other thought, so is it impossible to flood a tbi/tpi engine? I guess it'd still be possible.
 
You can probably listen for it, but it's just as easy to use a test light (or a 198 dash/marker bulb with wires twisted to the leads) and definitely more accurate.

It's possible to flood an injected engine, on one of these it would probably most likely be a result of injectors that leak.
 
I had a bad pickup coil cause a problem similar to this with my TPI setup awhile back. I could drive the truck for 30-40 miles and then it would start running like arse and eventually die like it wasnt getting any fuel. I had a 250 mile drive home and every 30-40 miles the pickup coil would get to hot and die out. I would let it sit for awhile and it would fire up and run fine for another 30-40 miles.

During my numberous times of sitting I was trying to diagnose the problem. I changed the fuel pump, every ECM relay, coil, ignition module, etc. The only thing I didn't change was the pickup coil. I had one but wasn't going to pull my distributor out on the side of a major highway unless I absolutly needed to.

I made it home eventually and changed the pickup coil and didn't have the issue anymore.

Harley.
 
Hossbaby50 said:
I had a bad pickup coil cause a problem similar to this with my TPI setup awhile back. I could drive the truck for 30-40 miles and then it would start running like arse and eventually die like it wasnt getting any fuel. I had a 250 mile drive home and every 30-40 miles the pickup coil would get to hot and die out. I would let it sit for awhile and it would fire up and run fine for another 30-40 miles.

During my numberous times of sitting I was trying to diagnose the problem. I changed the fuel pump, every ECM relay, coil, ignition module, etc. The only thing I didn't change was the pickup coil. I had one but wasn't going to pull my distributor out on the side of a major highway unless I absolutly needed to.

I made it home eventually and changed the pickup coil and didn't have the issue anymore.

Harley.
Click to expand...
I will check into that thanks
I have never heard of a pickup coil what exactly is it?
 
A pickup coil is located at the base of the distributor cap. It sits around the distributor shaft that spins in the distributor. To remove it and replace it you have to remove the distributor and dissassemble it.

Harley
 
When I had my '91 K5 I had the same problems, everyone told me it wasn't a fuel pump issue cause they always just go out. Well, it ended up just going out, on the side of the interstate. Sometimes they do gradually lose their prime or get hot and stop working. When you turn the key on after it dies, can you hear the fuel pump humming?
 
You must log in or register to reply here.

Latest Posts

Top Bottom