So today I could not get my pickup to start. Would turn over but would not start.

I have noticed a few times in the last month it sporatically would be a bit hard to start. Meaning I had to crank it over more than usual to get it to start. But it would always start. This was an occasional ocurrance. It acted a bit like it was flooded. Obviously that was not the case.

This rig has the 5.7 vortec and a manual 5sp transmission.

any thoughts. I do not think it is the fuel pump or module.
Does this unit have a computer that might be gunnybag?

Have the battery load tested, it might be holding a charge but not have the caa to start good, low battery power can play havoc with electronics as well

Any national parts store can test it and usually for free eliminate that then look for other issues

Why don't you think its the fuel pump? Does it ever bog down a bit when you put the hammer down?

If its not the pump, it could be the fuel pressure regulator. Do you have a fuel pressure guage? Fuel pressure should be between 60 and 65 on that engine.

Check the distributor cap. Sounds like you may have some moisture or corrosion in there.

Fuel or spark, both easy enough to test without any fancy equipment.

Thanks guys. Not the battery. It has a new one and a new starter. Cranks great.

I can hear the fuel pump when I turn the key on. It was changed in the 25k miles. Probably less.

Could be fuel pressure reg.

Could also be the dist. cap or something associated with spark.

What about the electronic brain. Does this vintage have one.

Thanks guys. I appreciate the thoughts.

Two things commonly go wrong with this engine - fuel pumps and injectors. This type of injector must have a minimum fuel pressure of 55 psi, even at the lower voltage present when cranking. If it only puts out, say, 51, 52, 53, it won't start. The other problem it has is the injector "spider" itself.



The large "body" in the center contains the electrical part of the injectors and the silver object is the fuel pressure regulator. At the ends of each of its "legs" are little poppet valves. These have been known to stick. When the engine finally starts it will miss for a few seconds until they become unstuck. This feels somewhat like the engine flooded. It can also leak. If you pull the upper intake manifold, everything should be covered with a layer of brownish-black crust. (This is normal.) Any areas that are clean and shiny are leaking because the raw fuel is washing them clean. If the fuel pressure regulator is leaking, a spot on the lower intake manifold below it will be washed clean. An improved "spider" that has the injectors out on the ends of the "legs" is available.

This message has been edited. Last edited by: egregore,

Thanks egregore, that sounds like a probable culprit.

Any rough estimate on what it would cost if that spider/injector deal needs replaced. I do not think i would attempt that repair myself.

Does it get harder and harder to start as the outdoor temperature rises?
Or load up at an idle?

If so, the IAC (Idle Air Control) could be the culprit.

A friend had a Chev pickup about the same era that had a problem I can't remember the details. The dealer diagnosed a bad distributer drive gear and he asked if he should replace it. I thought it sounded far fetched but replacing it cured the problem. Seems the distributor drive gear wore unevenly due to bad heat treatment and messed with the computer.

You might replace the drive gear on the come while inspecting all of the electrics under the cap at the same time. Do a google search of dist drive gear for this year make and model and see what you come up with.

I looked around a bit and my memory was jogged that the problem was an acceleration stumble, so this may not relate to your problem.

Check for fuel pressure and spark.

I would not rule out fuel pump. I had a Jetta that would leave you stranded at any given moment let it sit for a couple hours and it would start. Engine would crank but not start. Take it to the shop they could not find a problem, no codes nothing. After playing that game for a couple of months. It would not start at the mechanics shop until they found it was the fuel pump with an intermittent continuity issue in he motor.

Couldn't you pour a small amount of fuel down the throttle body then crank the engine to see if it fires? Alternatively while someone cranks the engine spray a little carb cleaner down the throttle body. In either case, if the engine fires you have narrowed it down to a fuel supply problem.

quote:

Originally posted by Gene Hillman:
Couldn't you pour a small amount of fuel down the throttle body then crank the engine to see if it fires? Alternatively while someone cranks the engine spray a little carb cleaner down the throttle body. In either case, if the engine fires you have narrowed it down to a fuel supply problem.

^^^^This^^^^
I had a 99 GMC Yukon. It dumped the fuel pump, one of the few issues I had with the truck. Once California eliminated MTBE from fuel, the injector issues pretty much went away on the vortec engines

I had a 1992 Yukon that when the plug wires would go bad, it would not start on damp mornings. That truck would eat plug wires.

quote:

Originally posted by F12517:

I had a 99 GMC Yukon. It dumped the fuel pump

Pretty common for the 99 models.
They must have changed suppliers (or manufacturing defect), as its not very common on previous years.

If you only turn the key to "run/on" does the pump hum for a few seconds and then quit? After you do that will it start?

[quote]If you only turn the key to "run/on" does the pump hum for a few seconds and then quit? After you do that will it start?
 
Yes it does and no it won't.

It had a new oem fuel pump put in 15 to 20k miles ago.

Try several key on engine off cycles before you crank. See if this builds fuel pressure and helps with starting. If so, suspect pressure regulator but pressure testing of the pump is necessary.


I lost count on the number of injection spiders I replaced due to a poppet failure. I also was seeing leakage near the pressure regulator due to cracking.The updated spiders are gtg.

Did you try pouring a little gas or carb spray down the throttle body as suggested? That should be pretty quick and easy and would tell you a lot about the problem. If the engine then fires you have determined that your problem is in the fuel delivery. If there is no change then you have to look elsewhere.

I'm old school, how many miles on the spark plugs?