hard starting - In the morning only

[BigRigTech]

I've noticed in the last few days that the 91 has been cranking a long time before it starts when I leave to go to work. When I leave to come home it doesn't crank near as long. I have IH glow plug troubleshooting sheet here so I'm going to test the system tonight. I can hear the relay clicking and the "wait to start" light is illuminating as normal. The only other thing that crosses my mind is it might be losing it's prime in the fuel system over night....Any common issues there with the dual tanks? This is my first 7.3IDI, I'm used to working on the big rig engines like CAT C-15's, 12.7 and 14L Detroits, N14's and etc....Not too much time spent on engines like my IDI.

 

[94johnh]

You have a common problem, How log before the wait to start goes out?
15-20 seconds ok less you may have 1 or more glow plugs out. Cause
#2 leaking return lines or caps. if any are wet get a new kit and install.

john

 

[adam g]

A common leak is the fuel hose from the steel line to the fuel pump. I have seen the steel lines where they come out of the tank get pinholes. Seen a few leaking filters.

 

[BigRigTech]

No visable fuel leaks anywhere and I just put a new fuel filter on last week, I did find 3 bad glow plugs though....Way over the 1-ohm or less spec on the sheet. Popped in 2 good ones I had and I'll grab a couple more tommorow. I'm going to check all the wiring too, got interupted by visitors tonight,...My wait to start light is shutting off after 3 or 4 seconds....I was under the understanding that the more glow plugs that are working the longer the light will stay on....Yes? No?

 

[adam g]

correct.

 

[Agnem]

It's easy to tell if it is glow plug related. Open the throttle all the way when you crank it and see if you get any smoke out of the exhaust. If not, it is air in the fuel, and not the glow plugs that are the problem.

 

[tonkadoctor]

No visable fuel leaks anywhere and I just put a new fuel filter on last week, I did find 3 bad glow plugs though....Way over the 1-ohm or less spec on the sheet. Popped in 2 good ones I had and I'll grab a couple more tommorow. I'm going to check all the wiring too, got interupted by visitors tonight,...My wait to start light is shutting off after 3 or 4 seconds....I was under the understanding that the more glow plugs that are working the longer the light will stay on....Yes? No?

It doesn't have to be leaking fuel to be getting air in the system, very common to be like this.

 

[BigRigTech]

I did think of something today that might be a possibility....This only started when I filled my truck for the 1st time and started using the rear tank....Until I filled it I was using the front tank. I picked up 3 more glow plugs today, I'll pop another in and see what happens tommorow morning. I want to finish checking the glow plug circuit and wires as well....I do get a little smoke on a cold start, just a small puff and that's it...I'll keep you posted. Hot as hell here today and I spent my day doing a head gasket on a 60 series Detroit...I'm popped.

 

[BigRigTech]

Check my GP harness, all good and in spec....Finished the glow plug trouble tree other than the dash light timing test....Everything appears to be working as normal. Cylinders #1, 6 and 8 GP's were all bad....3 cylinders in a row in the firing order.....Might have found the problem right there eh? I'll keep ya posted if it still acts the same and if it changes when I flip to the front tank this week....I'm loving the increase in fuel mileage over my 5.0....

 

[BigRigTech]

All is fixed I guess, I put the 3rd glow-plug in last night and this morning it started up almost immediately...Starting much better....Bring on winter....

 

[h2odrx]

All is fixed I guess, I put the 3rd glow-plug in last night and this morning it started up almost immediately...Starting much better....Bring on winter....

Hush!!!!!!!!

 

[adam g]

good news

 

[tonkadoctor]

All is fixed I guess, I put the 3rd glow-plug in last night and this morning it started up almost immediately...Starting much better....Bring on winter....

Be careful what you ask for, you might just get it.

Glad you got it figured out

 

[BigRigTech]

I hear ya....Winter will be here soon enough....I'll be ready with a brand new set of glow plugs and 2 BIG batteries... ....I've got a block heater timer too that is programmable - worked great last winter on my 96 F150 and the wife's Windstar.

 

[Michael Fowler]

Glad you found the problem.

However, remember what was said about air leaks. Unless you have installed an electric pump to PUSH the fuel, rather than the origianl mechanical pump which PULLS the fuel, you might never see the leak. If there is a pinhole, surface tension might hold the fuel in the line, but under suction, may well allow air to enter the fuel stream. This is especially true if you are still using the oen aluminum water seperator, which is subject to leaks. The best solution is to install an electric pump to just after the switch-over valve, and push the fuel to the IP. Remove the mechanical pump ( but keep the fuel heater line), and block off the hole using a Ch**y fuel pump block off plate.