So I drove to repair store and picke dup new Fram fuel filter. Still missing! Cleaned pick up screen out. It was pretty much plugged solid! Cleaned it up. Put new o rings in a put back together. Still missing. Fuel pump? Injectors?
Is there a easy way to check fuel pressure?
Thank you
Todd Santora

 

Oh sorry guys. Truck has 362,000 miles on it. But when its running right it runs great!
Thank you Maybe fuel pump??? Need to make my next step count and not waste money! Check fuel pressure I think should be next??

 

You can check fuel pressure with a cheap pencil type tire gauge. Check at the Schrader valve on the fuel bowl.

 

Is it a constant miss? Are you getting white smoke?

 

Hi guys,
Thank you for the quick responses. Well I went and rented a brand new fuel pressure gauge from OReilys and the pressure tested 48-50 psi at idle and dropped down to about 40 at 2000 RPM under load.
So I am assuming the fuel pump is fine. I have replaced the ICM in this truck 3 times. 2 times due to water getting into the module.
Last time I replaced it I put dialectric grease on the plug and pins and then sealed off the outside with silicone.
Its ran for probably close to 2 years with no real problems. I did replace all glow plugs, harnesses inside the valve covers and new valve cover gaskets about 4-6 weeks ago.
The Glowplugs where brand new motorcraft(made in Germany) and the gaskets I am not sure but they looked like a quality product.
I also replaced the glowplug relay. Starts fine now in the cold mornings! Was having a tough time recently and the glow plugs had never been changed in 362000 miles!
So I thought it was a fuel problem at first. Replaced the new fuel filter with fram filter. Still has the miss. And its almost like its in the whole motor. Today I took the screen out next to the fuel bowl. New o-ringed it and cleaned out the screen. Almost plugged solid.
Also, the ICM I replaced last time I am sure was not a high quality unit. 160.00 on ebay. They probably replaced the diode and threw it back together sealed it shut and sold it to me.
So I have the miss now. Or rough idle! Where before the motor would not move idling!! Super smooth.Do you think its the ICM again? Im leaning towards it! Anyway I can test it??? Any ideas?
I think I ruled out the fuel starvation problem. I have looked over the harnesses where they plug into the valve cover gaskets.
Could it be the CPS??? I have a spare in the glove box. Another motorcraft one. Im just thinking the ICM box is going south. Just hate to buy a 500.00 and find out its still not running right.
However, the last ones that went out on my I limped the truck home running on maybe 4 cylinders and no power.....
Thanks alot you guys!

 

Curt, no white smoke at all. Just a rough idle and lose of some power when accelerating.

 

I would try the CPS, can't hurt. If you have a buddy with a 7.3 try your IDM in his truck.

 

 

Thanks oldbird,
First I am going to test each glow plug for ohms. I have a plug i can plug into each harness at the valve cover. I can hook a ground up to the center wire and test each injector. Then I will test each glow plug too.
Im gonna double check my work just to be sure. If they all test out ok, then Its one step closer to being the IDM box in my mind.
Thanks 7.3! Yes i am trying to avoid having to pull the valve covers off. Save some work!

 

i will also check the continuity on my multimeter. I should be able to tell if a wire came look when I installed the new harness. I cannot image on did, as they have little clip/wire locks on each one of them.
That dam IDM box............

 

With it idling unplug each connector one at a time. The one with less or no rpm drop is your issue. Check wiring,ohm the injectors middle to each of the two on either side of it. You may find one whole bank is shut down. I'd resistance is equal across all injectors then I would agree on an idm failure.

 

The glow plugs have no impact on performance.

You really need to do some digital diagnostics. Check for codes, do buzz/cylinder tests, etc.

 

Hey guys,
HA! I fixed it. I took one of these plugs that came with the new gaskets and stripped the end off Then i plugged this plug into each gasket plug.



plug I used for testing
So, the center red wire is ground. Yellow and brown are injectors. Two outside blacks are glow plugs. I plugged this into each plug on the harness.
I tested with my negative on the red wire and pos. on yellow and then brown. Each inject tested at 30 ohms. Conductivity was fine and tested good.
When I got to the last injector on the drivers side closest to the front of the truck.....NOTHING!!!! No Ohms and no conductivity,
Pulled the valve cover. Pulled the harness of that side. Sure enough, the silicone seal had backed out of the square fitting that plugs into the top of the injector. Taking the wires with it!!! No connection at all.
I shoved it all the way back into the connector until this little silicone triple fin seal popped in and stayed in.
Plugged it back in and re tested. Got 3.0 ohms and conductivity was great!
Got it back together and its running great again! Do you guys know anything about the higher voltage diode mod to the IDM box to get like 25-35 more HP???
Thanks everyone for all the help! Sure runs alot better on all 8 instead of 7!!!

 

Actually, center wire is common POWER (120VDC) to the injectors. Yellow and brown are injector RETURN (switched ground) for the injectors.

Now you just gotta find an alternative to the McD's drive thru.....

 

Madpogue,
Thanks for the clarification! Im no electrician, but I can figure something out if im in a jamb! I bought a awesome Klein Tools tester. I love it. Still learning some of the symbols on it. Pretty cool though when you can make it work for you!
Yea im not big on mcdonalds. First time there in probably 2 years. Was in a rush and it was close!
This has been such a good truck I hate to give up on it. And on the freeway im getting just at 20 mpg. And it pulls my trailer no sweat!
The price of new trucks today is down right crazy!!!