AZbhoy

Hi gang, first post! Be gentle...
I have been reading this forum for a few days with the hopes of helping diagnose a problem which started about three weeks ago and has steadily grown worse. As I am disabled (bad arthritis in the hands and lower back is shot, use crutches) I now won't drive the truck for fear of being stuck; in more ways than one.
In my younger days I worked / overhauled many a motor; from MGA 1600 to Hemi 426 so I can at least speak the lingo and find the main parts.
I have read many a thread on this truck forum on everything from EGR, ECM, MAP, plugs and wires to what looks like the "dreaded fuel pump". My symptoms are within all of the above and I'm sure many other catagories.
The engine normally will start right up when cold but took a few turns when hot. It ran very smooth used maybe 1 quart of oil in 3K miles and the body is solid, no rust!! and suspension and tranny are tight. I'm not an agressive driver and unless I went up the mountain to Flagstaff the speedo rarely hit 50mph.
That was then, this is now: At first it spit once or twice, that progressed to spongy, flat spot when accelerating, then it started chugging and hesitating (worse going up a steep hill), required lots of cranking to start and finally would die when at a stop sign or coming away from a dead stop. This progressively over a three week period. It is now parked and too un-reliable for me to risk driving.
I am planning on having a certified? mobile mechanic come to the house to use one of those computer code reader thingie's and see what codes pop up. In addition, again based on many forum threads and the factory service and repair manuals I have, I am wanting to get the fuel pressure checked by the mechanic.
On several different diagnostic pages in the service manual it says normal fuel pressure is 9 - 13 psi as measured forward of the fuel filter. I read in the forum references to 60 - 66 psi. Whoa.... Which is it?
I read in the forum of a fuel pressure check valve. Where is it? There is no reference in the factory manuals that I can find.
Despite limited mobility/dexterity I have checked the plug wires, plugs, rotor, distributor cap and can find no cracks or evidence of arcing (crank the motor in the dark). Sometimes the engine will start and other times it won't. I can't hear very well so listening for the fuel pump to kick-in is a no go for me.
The truck is a 1990 CK2500 Silverado 2wd, 350cu.in, auto trans with 260K miles. I'm the second owner. In the past 5 years I have driven maybe 20K miles. Don't drive everyday and then maybe only 5 miles into town. The engine temp gauge often will not hit 190F. Might need some of that Seafoam stuff I've been reading about. ;-)
I don't have the funds to just throw money at it until something sticks; I do have lot's of time and patience. So, in an effort to get back on the road and keep this mechanic honest, any help or constructive and specific suggestions would be appreciated.
Apologies for the lengthy description.
Thanks.

2wd-K5

the lengthier the description the better the fuel pressure tester looks like a larg tire nipple, 30 psi is what i call normal fuel injected pressure, if it mainly happens at high rpms then i would suspect the fuel filter is old, when was the last time it was changed?
also, when was the last tune-up? the idle thing sounds like it may be from the plugs. i use dielectric grease on all fuel injected vehicles plugs and wires
i have also seen dist caps causing problems if they are old, if u do replace the cap and rotor ever, i recomend getting the ones with brass contacts the aluminum ones corrode almost instantly

AZbhoy

2wd-5K:
Thanks for the info.
Where exactly do I find this tire like nipple? I have looked and the only pressure nipples I find are on the AC lines.
Admittedly it is time for a tune-up. The plugs do however show a nice gray color and the electrode edges are still sharp with minimal rounding/wear.
I’ll go down to the local Auto Zone and get a new set of wires, rotor, brass contact cap and of course AC plugs and some silicone grease. We’ll see what results from that.
BTW: Went out this morning and if fired right up! Dang I hate that kind of thing.
<O</O
If there is anyone on the forum that can point me to a reference base/book etc.. that shows the fuel pressure numbers to be 60 – 66 psi or anything other than the factory manual 9 – 12 psi I would be most grateful.

Two Chevy/GMC dealerships I called had their service desk tell me 9 -12 psi for throttle body equipped vehicles and if someone is at 60 – 66 psi they must be running a direct fuel injected engine not a throttle body equipped vehicle.

Can any of you experts out there clarify or contribute to this item?

<O</O
Thanks

2wd-K5

hey if the dealer says so, it must be, make sure u get a fuel filter too

gaddyman

If that doesnt work try replacing the MAP sensor. I had the same problem until i changed it. u can get it from Autozone or Advanced for about 35 dollars

RacerX

The dealer is right. mechanical fuel pumps and TBI systems are low pressure FI systems. MPFI and Direct injection systems are high pressure systems. A 1990 is a low pressure FI system.

I dont know if you pursued this option, but what about an exhaust restriction? In the catalytic converter or muffler?

If the MAP sensor was not working then the car would not start at all.