First, vehicle info (haven't figured out how to create sig line yet):
1995 Suburban L65, mostly stock, utility model (rubber floor, vinyl bench seats, manual windows/doorlocks, etc.), PMD on finned heatsink behind bumper.
Refused to start last week, glowplug lamp (WTS) would not light, which gave a clue. Finally started after I momentarily jumped the two large screw terminals on the GP relay. I guess this freed up a sticky relay? GP relay is consistently working correctly now, GP light (pre-start) stays lit for a time that appears in accord w/ engine temp.
Resulting codes: 29, 62.
Ran fine for several days, until I noted minor bucking on the way home one night. The bucking seemed to coincide with driving over the expansion joints on the freeway, or other small bumps in the road.
Next morning, started fine, stalled sharply at 10 ft., started fine again, stalled again after 50 ft., would not start again.
Checked/cleaned grounds, esp. the two sets rear pass. side intake manifold, and the braided frame/engine/body straps.
Fuse inspection shows engine fusebox had some PO flakey addition, here is a photo:
The bare end of that orange wire was shoved into the cavity next to one of the legs of the Fuel Solenoid fuse (shown here sitting slightly crooked:
That orange wire energizes an (aftermarket?) relay on the firewall:
This solenoid power is supplied from the Aux B engine fusebox terminal. My guess is that this solenoid supplies the Tekonsha trailer brake controller. Is this common practice? Obviously the fusebox bare wire end "connection" is not accepted practice, but is the solenoid setup otherwise acceptable?
Back on topic--
Time allowing, I attempted to troubleshoot the no-start problem. Instrument panel lamps lit as expected, incl. GP lamp, good cranking speed. LP tested strong, approx. 1/2 quart in 10 sec. via the T-valve. LP would often continue to run 2-4 sec. after unsuccessful starting attempts. It really acted like bad PMD.
Bought a new PMD next day delivery from a best reputation supplier, swapped it in, still no start.
Carefully inserted paperclip in end of FSD extension connector to test voltage at pink wire, showed no voltage w/ ign. on.
Played with that Fuel Solenoid fuse in the fusebox, causing the Fuel Shut Off solenoid on the IP to chatter. Cleaned up and tightened the fuse receptacle, reinstalled the fuse, tested again the pink FSD extension harness wire (ign. on position), showed +12.34VDC! Getting closer! You can guess what happened next. Got the engine to start finally! Started several times equally well.
Resulting codes: 13, 81
On a hunch, swapped in the old FSD, engine started as well.
Remounted the (old) FSD/heatsink, engine still starts. Keeping the new FSD stored in the Suburban as a spare.
What can I do now to maximize reliability? Were the GP and fusebox issues related? The only thing I can think of is that it has rained heavily here recently and remember driving thru some big standing water a few times. Was the stubborn no-start condition really caused by a loose fuel solenoid fuse?
1995 Suburban L65, mostly stock, utility model (rubber floor, vinyl bench seats, manual windows/doorlocks, etc.), PMD on finned heatsink behind bumper.
Refused to start last week, glowplug lamp (WTS) would not light, which gave a clue. Finally started after I momentarily jumped the two large screw terminals on the GP relay. I guess this freed up a sticky relay? GP relay is consistently working correctly now, GP light (pre-start) stays lit for a time that appears in accord w/ engine temp.
Resulting codes: 29, 62.
Ran fine for several days, until I noted minor bucking on the way home one night. The bucking seemed to coincide with driving over the expansion joints on the freeway, or other small bumps in the road.
Next morning, started fine, stalled sharply at 10 ft., started fine again, stalled again after 50 ft., would not start again.
Checked/cleaned grounds, esp. the two sets rear pass. side intake manifold, and the braided frame/engine/body straps.
Fuse inspection shows engine fusebox had some PO flakey addition, here is a photo:
The bare end of that orange wire was shoved into the cavity next to one of the legs of the Fuel Solenoid fuse (shown here sitting slightly crooked:
That orange wire energizes an (aftermarket?) relay on the firewall:
This solenoid power is supplied from the Aux B engine fusebox terminal. My guess is that this solenoid supplies the Tekonsha trailer brake controller. Is this common practice? Obviously the fusebox bare wire end "connection" is not accepted practice, but is the solenoid setup otherwise acceptable?
Back on topic--
Time allowing, I attempted to troubleshoot the no-start problem. Instrument panel lamps lit as expected, incl. GP lamp, good cranking speed. LP tested strong, approx. 1/2 quart in 10 sec. via the T-valve. LP would often continue to run 2-4 sec. after unsuccessful starting attempts. It really acted like bad PMD.
Bought a new PMD next day delivery from a best reputation supplier, swapped it in, still no start.
Carefully inserted paperclip in end of FSD extension connector to test voltage at pink wire, showed no voltage w/ ign. on.
Played with that Fuel Solenoid fuse in the fusebox, causing the Fuel Shut Off solenoid on the IP to chatter. Cleaned up and tightened the fuse receptacle, reinstalled the fuse, tested again the pink FSD extension harness wire (ign. on position), showed +12.34VDC! Getting closer! You can guess what happened next. Got the engine to start finally! Started several times equally well.
Resulting codes: 13, 81
On a hunch, swapped in the old FSD, engine started as well.
Remounted the (old) FSD/heatsink, engine still starts. Keeping the new FSD stored in the Suburban as a spare.
What can I do now to maximize reliability? Were the GP and fusebox issues related? The only thing I can think of is that it has rained heavily here recently and remember driving thru some big standing water a few times. Was the stubborn no-start condition really caused by a loose fuel solenoid fuse?