need a little help - glow plugs or fuel pump?

[OB_WAN]

a few months ago my truck got a new moose pump and some new injectors. shop did a great job. they warned me my lift pump was leaking a little but I didn't have the cash to get it fixed at that time.

about a month ago, the truck went dormant for a while. when I got back to it, it had a tough time starting. has an electrical short somewhere so is slowly draining battery. got it jump-started for a trip. during the trip, if I let it sit for a long period of time(8+ hours), it would be tough to start. take 10+ seconds to fire, would rough idle for a bit blowing white smoke, and then smooth out/clear up. I thought it was just air in the fuel line due to the leaky lift pump.

well, the problem is now a lot worse. tried to start it the other day and killed the batteries(probably already partially drained from voltage drain) turning it over. thought something was wrong with the lift pump so charged the batteries and while they were charging, loosened the fuel filter to see if it had fuel. was completely full. tightened it back up and about 20 mins later tried turning over the engine. it fired IMMEDIATELY. great idle. note: when trying earlier it was prob about 45 degrees out. when trying the 2nd time, it was ~65 degrees out.

Okay, fast-forward a couple of days to today(I drove it yesterday and last night no prob). had been parking it nose down to reduce air in fuel lines in case that was the problem(sloped driveway). worked for me in the past when I had injector return leaks.

I went out this morning to start it up. it was about 35 degrees out. was turning it over and it wouldn't fire. tried a few times. on the third attempt, it acted like one of the cylinders was trying to fire: on each rotation, it seemed like it would fire but wasn't enough to get the mass moving. all this time it's blowing white smoke out the tailpipe. gave up. didn't have time to check it today when it was warm out.

So... At first I thought the problem was the fuel. after re-occurring problems and two specific problems when it's cold out, I'm now thinking that either something is wrong with the glowplug relay or the plugs themselves are done.

Any thoughts? any suggestions for diagnosing the problem (in newbie language?)

 

[OLDBULL8]

Pull one of the wires off a glow plug, easiest one to get at, check for voltage 6-12 volts. Have someone try to start. No voltage--GP controller or GP relay. Your getting fuel (white smoke). No start cold. Start when warm.

 

[icanfixall]

Find the engine main wireing harness plug... On my 89 its on the passenger side fender well area. See if its melted or hot when you have cranked the engine... If so its a bad connection of the glow plug main power feed lines... Those two yellow wires feed power to the controller. Any corrosion in the plug fitting will cause melting. I bypassed mine with some 4 gauge speaker wire from an audio sound shop... Now the power comes directly from the fender solenoid to the controller. Look closely at the fender solenoid and you will see the battery power feed uninterupted directly to the controller... So its hot all the time... Be carefull... Lots of amps at the controller end of that wire. Any grounding and you have an instant burned up wire... 2000 amps flowing to ground thru that two tiny wires melts quickly....

 

[OB_WAN]

Just as I hoped. And just in time to see the post for the smokin deal from Uhaul on glow plugs and relay.

 

[OB_WAN]

Find the engine main wireing harness plug... On my 89 its on the passenger side fender well area. See if its melted or hot when you have cranked the engine... If so its a bad connection of the glow plug main power feed lines... Those two yellow wires feed power to the controller. Any corrosion in the plug fitting will cause melting. I bypassed mine with some 4 gauge speaker wire from an audio sound shop... Now the power comes directly from the fender solenoid to the controller. Look closely at the fender solenoid and you will see the battery power feed uninterupted directly to the controller... So its hot all the time... Be carefull... Lots of amps at the controller end of that wire. Any grounding and you have an instant burned up wire... 2000 amps flowing to ground thru that two tiny wires melts quickly....

Okay, got back under the hood the other day to look for the harness you were talking about. Well... The harness plug is melted where the two wires go in. The wires look burned and partially melted at the harness and @ the controller. Touching the wires after turning on the glowplug controller for a short time = hot wires.

Heading down to the electronics or car audio store later today to grab some 4 gauge and connectors. I had some 8 gauge car audio amp wire that MIGHT work but looking @ the specs of 10 gauge x 2 vs a single 8 gauge, don't want to risk it. 4 gauge is a little bit of overkill but "go big or go home" is a common thought since I bought this truck

Thanks a lot for this tip. Any other wires I should be looking at for possible melt-down issues?

 

[SparkandFire]

I did 4 ga on the '87 and it worked great!

BTW, I work in roseville, and I have all the connectors and the cable if you want to come by my shop sometime, I could fix you up a cable...

 

[Silver Burner]

If the harness is melted, will the wait to start light still come on for 10-15 seconds, or will it just click off quick?

 

[OB_WAN]

Sparkandfire thanks a lot for the offer. I just picked up a 4g battery cable and a couple of connectors for$ 10. Not the cheapest but wont kill the bank. Otherwise I'd definitely take you up on that offer.

Silverburner the light still comes on as expected. Looks like only the side of the harness where the two power feeds are at is melted. Unfortunately I think the harness is fused together so can't check for corrosion/connectivity issues on the other wires very easily. Worried if I force it apart i'll screw up the other connections. If I have issues down the road i'll replace the harness.

 

[SparkandFire]

Good to hear you've got the parts worked out.

I've got the whole Thomas and Betts connector set, with the crimp tool. I use it alot for terminating big motor leads, so it's nice to have on hand.


Although on this big guy we had to use a much bigger crimper...

A 1200 HP M&M Chiller we just commisioned.