My 96 PSD is hard to start in cool weather. I read a wonderful post on here about testing for the GPR. I performed the test which included crossing out the GPR to determine if in fact the relay was bad. I did. When the relay was crossed out I had power to the GP's. Bingo! All I need is a GPR. Wrong! When I started the truck for the trip to the parts store it was running on 6 cyl. No smoke, nothing. Just a dead miss. Truck has 190,000 miles and did run like new.
What did I screw up by crossing out the GPR?

Thanks,
Justin

 

Welcome to FTE Justin!

Jumping the relay doesn't do anything that doesn't normally happen when the relay is working properly, but.....since the wiring harness for the glow plugs and the injectors run through the same plugs in the valvecover gaskets, you might have inadvertantly found a short in the harness.

Can you tell which bank isn't firing correctly? That would make it a simple matter of pulling the valvecover and inspecting the harness on that side.

 

Thanks for your reply. That makes sense. I only checked the passenger side. Logical bank would be that side. Can I run a test before removing the valve cover to determine if it is a wiring problem under the Valve cover? Can the cover gasket be saved?

 

You can pull the connectors at the valvecovers and inspect that side of them, there are two connectors on each gasket. Front and rear of the inside face. Assuming the harness connectors are not melted the gaskets are reuseable.

If you know somebody with a good scan tool, or want to take it to the dealer, you can have a cylinder contribution test done and that will tell you which injectors aren't firing.

 

Thanks again. I pulled the connector off the front of the right bank this morning and it looked new. I inserted my test light into the terminals on the conector to check the relay. I did notice it was only hot on one of the conector terminals when I crossed out the relay.
I am going to take your advice and carry the truck to the shop tomorrow and let them run a test.

Thanks,
Justin

 

Hey Cookie.......Took the truck in this A.M. was told to leave it and they would try to work it in today or tomorrow. That means after they get out this weeks work so they can get paid for what they have started before payroll cut off for the week. Right?
I agree with you that it has to be wiring. Say they do run the test. It will only show one or two injectors down not why they are down. Right?

The wires going to the harness are for both GP's and injectors. Right? Which wires are injectors and which are GP's? Where would you start to test the wiring on top before pulling the valve covers?

Knowing the GP relay is bad would you start with replacing the relay? Could the relay be grounded out causing the problem or is the relay on a separate circuit from the injectors. I assume that it is, just banging my head for answers.
Need the truck this weekend to pull my fifth wheel to the mountains. If the truck is down my girlfriend will be wearing a frown.

 

When they pull the codes each injector might have a code like this

0261* INJ Injector ckt low - Cylinder 1 FMEM mode, engine will run on 4 cyl. Harness short to ground

0262 INJ Injector ckt high - Cylinder 1 FMEM mode, engine will run on 4 cyl. Miswired connector or harness

0263 PCED Cylinder 1 contribution/balance fault Cylinder not contributing during CCT test Power cylinder, valve train or injector problem, circuit

I am pretty sure the outer connectors are the GPs
Ya I would replace the GP relay for your hard start problem, it sounds like these are two different issues

Hope they get you fixed up before the weekend

 

Thanks Foreman for your reply. I feel better now knowing the test will show more than a bad injector. This is my first diesel powered truck. I did teach auto mechanics back when we had a test light, a pair of aligator clips for a jumpwire and a multi meter. Thanks again for your help.


Justin

 

Ya and you guys are still some of the best mechanics out there. They will (should) also run a injector buzz test, it will let you know if any of your injectors are weak our worn out. I bet you had a simple wire harness problem. Dont be afraid to get out you tools and mess around with these trucks, you could have easily replace the harness plugs, and the GPR is a 5 minute swap, dont pay someone to do that. When you get it back tell us what it was.

 

Thanks Foreman. We were more than electronic parts changers.
Got a call from the shop on my PSD running on 7 cly. They are saying it's the number one injector and want $300 for the parts and 3-4 hours labor.
I find that hard to believe since it was running perfect before i tested the GPR.
What do Ya'All think about the report and the price to replace the injector?