1999

rjgti · April 15, 2009

truck started running rough tonight. stalled 2 times. cannot hear fuel pump at all anymore. has whined for 6 years. will put a gaguge on it tomorrow. what is rail psi. 70 psi. what is leakdown when shut off? strange i just cleaned and reoiled my air filtler. drove 400 km without a problem. started truck and when i get on the gas it hesitates and misfires. not bad enough to light a code. i've done this airfilter 10 times with no problem, i took air filter of and inspected it and there is no sign of over oiling. just starting to sink my teeth into this. any ideas?

mr_bots · April 15, 2009

Since it's an oil air filter, might try cleaning the MAF, if it's dirty it can make it run and act really weird.

08SGMSierra · April 15, 2009

truck started running rough tonight. stalled 2 times. cannot hear fuel pump at all anymore. has whined for 6 years. will put a gaguge on it tomorrow. what is rail psi. 70 psi. what is leakdown when shut off? strange i just cleaned and reoiled my air filtler. drove 400 km without a problem. started truck and when i get on the gas it hesitates and misfires. not bad enough to light a code. i've done this airfilter 10 times with no problem, i took air filter of and inspected it and there is no sign of over oiling. just starting to sink my teeth into this. any ideas?

If you FP is not longer making noise I would start there. Also, when was the last time you checked/replaced your plugs/wires? I had a similar problem this winter with my 95 Caprice. Sometimes it would run fine, then it would darn near shut off for a second, then kick in. Some of my plugs were bad, and a few wires were iffy. That solved it, runs good as new now.

HTH.

hockeypro1411 · April 15, 2009

My god. People should have to pass a literacy test before they're allowed to post...

08SGMSierra · April 15, 2009

Wanted to add my co-worker has a 99 LS Silverado and he just turned 100k. He has all kinds of driveability issues and it took the dealer several tries to correct it. He had a bad ground, plugs/wires, and I believe a fuel problem as well.

rjgti · April 15, 2009

anyone know what the fuel rail pressure should be? is it 70 psi. will be measuring after work today. and i've never heard of cleaning a mass air flow sensor, when they become contaminated they are finished. plugs and wires are good.

pennzoil29 · April 15, 2009

anyone know what the fuel rail pressure should be? is it 70 psi. will be measuring after work today. and i've never heard of cleaning a mass air flow sensor, when they become contaminated they are finished. plugs and wires are good.

CRC makes a good cleaner. Follow the directions on the can.

rjgti · April 15, 2009

i will have to search for crc. do you remove and spray air meter edit: just google crc and no hits for cleaner.

pennzoil29 · April 15, 2009

i will have to search for crc. do you remove and spray air meter edit: just google crc and no hits for cleaner.

http://www.crcindustries.com/auto/content/...=Y&PN=05110

Lincoln30 · April 15, 2009

If your truck is starting on the same number of cranks as it did before it started running rough then your shutoff fuel pressure is fine. If that pressure drops below where it should be your truck will crank a lot more before it will start. I think 59-62psi is correct???

I'm in the "clean the MAF camp" on this problem. I've always done it with a q-tip and alcohol but the spray seems like a safer (but more expensive) way to accomplish the task. It's cheap and easy to try this before you tackle plugs/wires and the fuel pump.