View Full Version : stalling and running rough not the PMD
My truck started running rough and would stall after it was hot. I did some checks that I found on this sight and decided the PMD was bad. Bought new PMD ouch and remote cooler and installed. No change same old stuff. Some observations are as follows No SES light, Truck seems to run fine while accelerating most of the time. The truck will stumble and stall at an idle unless I 2 foot with the throttle and then it will stay running. I also can hear an audible fuel timing rattle and then it will go away and come back very spotty but it happens. Now I think I hear a rotating noise from the injection pump kinda like a playing card on bicycle spokes but much faster. Fuel pressure is 4.5-5 psi at all times. Fuel filter has been changed. Check battery connections and checked for voltage drop. All good. I have not yet put additive in the tank. I will do that tonight.
93GMCSierra
10-02-2007, 15:51
possible that the fuel injection pump is dying.
Thats what I was thinking. More news. I notice that when there is an electrical load it starts to run rough. Example turn on the ac truck starts missing then smooths out. Same with headlights brakes etc. I must be missing something electrical. Anyone have an Idea?
Artworks
10-02-2007, 18:26
What are your voltages of both batteries ? I had one battery that was poor and would draw thew other down. Each battery should have 13+ volts. Get both batteries load checked. My truck would start to run poor, I put charger on over night and bring them up. Whould run a lot better for few days and then it would begin to run s -itty again . Replaced one battery after a load test showed it wasn't up to snuff, Alternator gave up couple months after also. Hope this helps.
What are your voltages of both batteries ? I had one battery that was poor and would draw thew other down. Each battery should have 13+ volts. Get both batteries load checked. My truck would start to run poor, I put charger on over night and bring them up. Whould run a lot better for few days and then it would begin to run s -itty again . Replaced one battery after a load test showed it wasn't up to snuff, Alternator gave up couple months after also. Hope this helps.
My cable from left to right battery looks like might have a bad spot. You might be on to something.
The alternator feeds the LH battery. The crossover cable brings the power to the RH battery. The power feed to the truck on the 94 is via the #4 cable that runs down past the starter and up into the junction block on the firewall by the AC accumulator.
The ground cables can and o go south on both ends.
The crossover cables also go away.
Use a good volt meter ans check the voltage at both batteries. Running at idle you should see 14.2 to 14.7 at the batteries. If the RH battery is not getting good voltage and you have issues on the feed line the power to the computer may be falling off.
Low power will cause all sorts of crap to happen.
If the cables are the original or ??? they probably need replacing.
You cant see really whats inside them without cutting them open.
You can reroute the power feed from the RH battery and run it up and inside the engine bay and over to the junction if you replace the old one.
With a computer controlled rig the voltage is very important.
If the crossover cable is bad or the ground on the LH battery is bad the circuit wont complete and this causes tons of grief.
Check this stuff out well and let us know.
Robyn
the cables are vintage 1994 stuff. I am going to replace them. Now the truck has stored codes 18 and 19 but no SES light. Battery voltage is same for each battery 13.1. engine running 14.3. I did not know about the power feed at the firewall I will check it out tomorrow.
dropped about $700 on this deal but ended up with new bat cables, pmd with remote mount cooler, clean electric terminals everywhere, Fuel filter, and other maintenance items that I should probably have done anyway. The problem was the OS filter. Removed it truck ran fine all day. Reinstalled and it ran like crap again.
Artworks
10-03-2007, 17:44
Forgot about the o/s filter, I had that happen too! Don't ya just love the electrical gremlins in these trucks ! Makes patience a real art !!! But is a joy once ya figure it out and get it fixed, like a home run or a touch down!
signgrafix
10-05-2007, 10:12
What is the o/s filter?
DmaxMaverick
10-05-2007, 12:30
What is the o/s filter?
Optical Sensor
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