"New" superduty woes

[ISPKI]

Hey all,

So I got this 94 Superduty 7.3 NA. Truck was fairly well maintained, has 200k on it. Looks like they put a fair amount of new OEM parts into it.

I'm working thru alot of the usual items, injector O rings have been replaced, caps no longer leak. Replaced the fluids, oil filter, fuel filter, batteries etc.

Truck takes a while to start. Seems like air intrusion or GPs maybe. The GPs cycle only for a couple seconds even when it's pretty cold and then start clicking on and off. My old truck never did that clicking thing so not sure what that is. The connectors in the GP harness are all crumbled. I can get the truck to start if I hook up my charger to it at 250amps but takes a solid 45 seconds to a minute of intermittent cranking. When I hit the shrader valve on the filter head it spits a tiny bit of air.

Going to pull a few of the GPs next and see what they look like. Anything else I should be checking? Maybe I should replace the fuel return lines and caps while I'm at it.

 

[ISPKI]

Forgot to mention. Once it starts up. I can restart it easily. Restarted after sitting for half an hour in one crank so it seems that the IP is healthy or at least healthier than my other truck's.

I seem to recall there being a seal in the lift pump to filter head hardline that commonly went bad. The injector caps O rings crumbled when I pulled them off so likely hadn't been changed in a long time.

 

[cozinsky]

Have you tested the glow plugs? Unplug all of them, clip a test light to the positive battery post and touch the tip of each glow plug with the test light. If the light comes on they should be good.

 

[snicklas]

What you are describing is definitely a glow plug issue. The couple second glow and then the clicking (afterglow) indicates the controller is thinking the plugs are hot, when they are not. So either bad connections, or burned out plugs, or both...

Easy check of the plugs is to get a test light, hook the alligator clip to the battery positive, unplug the plug from the harness and touch the probe to the glow plug. If the light, lights, the plug should be good. No light, bad plug. Could be a bad solenoid for hte plugs. If you have a volt meter, measure across the 2 big lugs when the WTS is on... you should see almost no voltage reading, If you have up vear 12 volts, the solenoid is not conducting....

My best guess is bad plugs.... every IDI I have bought (except 1, and it came from someone that knows IDI's) has had bad glow plugs in it.....

 

[Farmer Rock]

I agree with @snicklas , it sounds like a GP problem for sure. I would suggest replacing the GP harness when you do the GPs. The harness definitely isn't helping the way it is.








Rock

 

[IDIBRONCO]

I'll agree with the glow plugs, but I feel that you also probably have a fuel drain back issue since you said that you get a spurt of air when you push on the Schrader valve. The glow plugs will be easier to check so I'd do that first.

 

[Fredrickson]

Sounds like you have my truck.. GP issues, air intrusion.. oh wait.. that's pretty much most IDI owners at some point..

I ended up replacing all the glow plugs, and the controller.
When I disconnected the wires from controller.. it fell apart.

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[ISPKI]

Ya all are awesome. I put together a check list of items to check/replace, Glowplugs are first. I popped them out and low and behold, 8 autolites, all caked in a crust of carbon and 7 of them clearly swollen. I've never actually had a GP swell so wasn't sure if I'd notice. These are pretty clear. Got a set of motor craft ZD9s coming in at my local parts store tomorrow and I'll order up another harness from CDD. I got one for my old truck and was impressed with the quality and affordability.

 

[ISPKI]

Well I replaced the fuel filter and Glowplugs. Truck primed for a solid 8 seconds and then fired up in half a crank. Amazing how much those plugs effect it. Truck died after a few seconds, assuming I need to purge the fuel system of air since there would be a pocket in the filter head after replacing the filter.

 

[Farmer Rock]

Well I replaced the fuel filter and Glowplugs. Truck primed for a solid 8 seconds and then fired up in half a crank. Amazing how much those plugs effect it. Truck died after a few seconds, assuming I need to purge the fuel system of air since there would be a pocket in the filter head after replacing the filter.

That's for sure. My trucks won't start in the summer without at least 4-5 seconds on the GPs, and we are talking probably 80 degrees average. That has thrown me for a loop quite a few times when trouble shooting a problem on the spot. It's good to hear you got it going again! Did you fill the filter up before installing?





Rock

 

[ISPKI]

Yeah I filled it with some diesel treatment, ATF, I had saved the fuel from the old filter expecting to use that but it had some debris floating in it so I got rid of it. I'll have to crack the injector nuts and bleed the system out for a bit.

I had installed a duralift pump on my old truck. Kinda wish I had it on the new truck. Other part of me wants to keep it stock for as long as possible.

 

[Farmer Rock]

Yeah I filled it with some diesel treatment, ATF, I had saved the fuel from the old filter expecting to use that but it had some debris floating in it so I got rid of it. I'll have to crack the injector nuts and bleed the system out for a bit.

I had installed a duralift pump on my old truck. Kinda wish I had it on the new truck. Other part of me wants to keep it stock for as long as possible.

Stock? What's that? Lol. I think we all say that, but it don't last long. Electric pumps certainly are nice.



Rock

 

[1mouse3]

Stock? What's that? Lol. I think we all say that, but it don't last long.

Stock, is that where the bucket of parts that makes up the truck can readily be found in the junk yard?

 

[The_Josh_Bear]

If you just add a check valve between the filter header and the lift pump your drainback issues will be cured, unless you are leaking air into the filter via the fuel heater or if the old-style filter then the bottom oring.

You can also get a replacement check valve for the one in the filter header that goes to the #1 injector return line but even a brand new one wasn't anything to write home about for me. A diesel rated check valve in the supply line is more effective in my experience.

 

[ISPKI]

Stock, is that where the bucket of parts that makes up the truck can readily be found in the junk yard?

"Stock" is my collection of salvaged parts from years of tearing apart wrecked trucks that are now strewn all over my work tables.