I'm helping my nephew get a 1988 7.3 on the road. He's 16 and it's his first vehicle and diesel. The DMF was pooched so we put a LUK SMF kit in and that went great. No noise and the clutch feels great.

But we're having issues with starting it. The WTS light would only come on for maybe 2-3 seconds and it was hard to start and would run rough until warmed up. Once warm it starts fine and runs well. The motor is crisp and responsive. Oil pressure is around 20lbs hot at idle. The truck only has 95,000km/56,000 miles total. And no the odometer hasn't rolled over. It's a Canadian truck so it has an extra digit in the odometer so it's either 90,000km or 1,090,000km. The truck is far too clean to be a million+.

I started by checking over the engine. The glow plug relay was melted and in very poor shape so I changed it with a NAPA part. The GP's were still cycling 2-3 seconds. The brand of GP's were unknown to us but the tops looked different than the ZD9's in my plow truck so we ordered a set of ZD9's. Thankfully we did because the truck had garbage Autolite GP's. 6 came out easy and two had to be worked out. They had all started to swell and 5 of 8 were reading open and 3 were 0.8 ohms. We got them changed and still only 2-3 seconds. The truck seemed to be turning over fine but I threw a battery charger on it and it was only reading about 25-30% charged so I'm hoping that is why the new ZD9's are still short cycling.

But another issue we have is that sometimes you go to start the truck and there would be nothing. No starter. I realized jiggling the steering wheel side to side would cause it to turn over. What could be causing this issue with the steering wheel? Any advice on what else to check if the batteries aren't the issue?

 

The steering wheel shouldn't be connected to the starting circuit, but its possible the linkage that runs down the steering column is worn out, especially if its a tilt column. May need to disassemble and clean it up in there to see what is going on. Should be a few threads on how exactly it all comes apart.

Even though you changed the glow plug relay, there is a chance the controller is messed up causing the short cycle. Also what shape is the harness in? Maybe some of the wires are broken/corroded not sending voltage to some of the plugs causing the controller to misbehave? Something to check.

 

Two different issues ... Ones is an ignition switch issue, the other is a glow system issue.

A short cycling glow system is a sign of to much resistance ...

That typically means bad glow plugs, it can also mean bad connections ... Including a weak connection in a CRAP relay!

CRAP = Chinese Repair Auto Parts!

The glow plug controller senses resistance, as the glow plugs heat they increase in resistance. Bad connections increase resistance as well.

As you seem to know, Good batteries are an absolute must.

-Enjoy
fh : )_~

 

BTW, If you haven't read the Glow Plug stickies, I recommend you do, both of them, they both provide valuable info.

-Enjoy
fh : )_~

 

Thanks guys. If the Napa Relay is junk, what brand do you guys recommend? I bought it because it was mentioned in the GP stickies. The bullet connectors seemed tight but if the issues continue after the batteries are fully charged, the next step is checking the controller, wiring harness, etc. We might pull my relay and controller off my plow truck to see if that cures the issues. I just figured the controller rarely goes especially with such low mileage. We might just make our own GP harness.

 

Have you thought about wiring the glow plugs to a switch instead? My buddy had his wired to a push button and it starts great every time he has to use it.

 

And most do this dangerously ...

A good operating system does the job perfect!

-Enjoy
fh : )_~

 

You don't have a lot of choices in this engineered life span world unfortunately!

If you do build your own harness, remember the controller works on resistance, messing with the resistance of the wiring affects the controller.

If you choose (I do not recommend) to doing a manual switch, all you need to do is remove the white wire from the relay and ground that terminal (not wire) via a switch! No powered switch or wires necessary!

If your plow truck glow system works fine, I would recommend pulling the relay at least and testing with it, it's just as easy to swap the whole unit though!

And just for safety ... Snap a pic of it's hookups before removing it!

-Enjoy
fh : )_~

 

So I fully charged the batteries and it still was short cycling. Moved on to the relay and had 13.06 volts to the big constant terminal. Before going further, I noticed the metal zigzag resistor and the two wire eyelets were loose where it bolts to the top of the GPC. I took it off and saw some arcing pits on the bottom of it. I cleaned up all the eye connectors for that terminal including cleaning the zig zag mounting surface with a dremel and reattached everything. The GP's came on longer but still only about 5 seconds. It fired but was rough and stalled. Second time about 5 seconds again, feathered the pedal and it kept running. There was hardly any smoke from the exhaust. I let it high idle for a few minutes and drove it up and down the driveway a couple of times. I parked it and tried to restart it. The WTS light was on maybe 2-3 seconds and it fired right up. I just went out after it sat for 10 minutes and the light only came on for about 2 seconds. It's about 23C/75F outside so I'm not sure if 2-5 seconds is ok when it's warm out or whether it should be longer.
Before I fixed the resistor the WTS light was on about 2 seconds when the truck was cold and the truck didn't want to start. If it did start, it smoked white smoke(unburned fuel) until it warmed up.
It has new ZD9's and the relay was put on last Fall and used very little due to clutch being bad. So should I move on to the wire harness and then the GPC?

 

How long they are on does depend on Temperature and Battery condition ... In a proper operating system.

The only way to know for sure is to see how it does first thing in the morning when it's the coldest.
Hardly any smoke says a lot ... If there was cold cylinders it would puff white smoke!

Not saying it's this, but leaky injectors can make for a rough run on start up without much smoke.

It's been setting, I do recommend pulling the fuel filter and filling it with Diesel Kleen or the like, start it let it run for a minute, shut it off and let it soak for a period, longer the better to a point. overnight/all day is good.

-Enjoy
fh : )_~

 

With the bad clutch it sat for at least a year. Not sure how long it sat before we got it. We were planning on doing the fuel filter/diesel kleen once we got it running. I do the same thing with my plow truck every year. With 13.06 volts to the relay, I'm assuming the batteries are good. They're only about 2-3 years old. The battery cables outer sheathing is split in a few places so we need to change those when he has more cash.

 

That's a measured voltage and means little or nothing ... One copper strand can pass that but not the amps required ... A drop test is whats required.

If you don't know what/how a drop test works, read this Voltage drop testing how to fix that slow starter

It's a good read if nothing else!

EDIT:
Have you felt all the GP wiring for heat when in operation a bad connection will produce heat.

-Enjoy
fh : )_~

 

Thanks. Just went out and started it again. It's +80F outside. WTS was only for 2 seconds but it fired right up with no smoke. It ran rough for a few seconds again but smoothed right out. So a new filter and diesel kleen is next followed by checking the injectors.

 

On my 94, When it's +80F out and is not the first start of the day, the GP's come on for about 5 seconds if that!

First start of the day, about 7 to 10 seconds ... A bit longer when below -10F.

-Enjoy
fh : )_~

 

They're only coming on for about 2 seconds so we must still have issues I guess??? Unless brand new GP's need less time to heat up. After I fixed the loose zig zag resistor earlier, they stayed on for about 5 seconds with the motor cold and outside temps around 75F