Well I am in need of some assistance.

I have a 97 7.3 F350. On Thursday last week I went out to check things over in order to get ready to take a horse to the vet. The truck has not been driven since April so I thought a quick check to make sure it still ran would be a good thing.

The truck started up as normal and ran for a while. Since it's been so hot in Houston I decided to put a little 134a in the system. Then all of the sudden it was like someone turned a switch and the engine started running rough like low on fuel or sucking air. I turned it off went to the parts store and picked up a new fuel filter. Replaced it, and it started back up and ran normal.

On Saturday dove it about 50 miles and while costing to a red light I could tell the truck was not running right. Got to the light and it was like running on 4 cylinders, or sucking air. Barley had enough power to the trailer and horse off the road.

Long story short while trying to figure it out on the side of the road I heard a click and like a switch it started running normal. Drove home and then about 3 miles from the house started running bad again.

No CEL, no smoke, fuel bowl full, screen clean. Checked valve cover connections and no burnt pins and all were good and clean. Tach moves so the CPS should be okay.

 

Ok guys. I see that you all are reading this but no replys. Should I be getting concerned?

Any ideas?

 

Check injector harness connectors on valve cover harness for burnt/melted pins. Possible bad connection being made, seen before.

 

No big deal, it just means that the real experts on this sort of thing aren't here yet. I am going to tag a guess and say that you need to look at your ICP. The ICP senses the pressure in the high pressure oils system and adjusts it through the IPR. If the ICP is not sensing the pressure correctly, the IPR will not be adjusting the High Pressure Oil to the injectors like it should be. Both sensors are on the back side of the HPOP. Hang on, I am looking for a picture...

 

OK, here is the one I was looking for:



Try unplugging the ICP and running it that way. It may be hard to find this issue since it is intermittent, but with the ICP unplugged, the IPR goes to a set value that should be enough to run the truck a little while to test whether this is the issue.

As I said, this is not my area of expertise exactly, but it is a fairly well educated guess. If nothing else, it will serve as a bump so that someone else can see this thread and correct me if I am wrong.

 

Well I unplugged the ICP and try running it that away. It was a lot harder to start and it would not stay running. Plus the CEL light came on. I guess it's safe to say that the ICP is not the issue.

Any way to test the IPR or do I just go pick one up and try it?

Again the valve cover harness connectors look great. Any way to test those?


And as always your help and advice is greatly appreciated.

 

You may have under valve cover wiring problems. I think there is a way to test the outer pins, I just don't know it for sure. Hope someone pops in and helps you with that.

I'm thinking you have harness problems somewhere, not the ipr.

Any check engine light come on? Have you tried to pull codes?

 

It's interesting that when you loaded up the 134, it acted up. My first thought was that the compressor may not be spinning correctly, or a bearing getting ready to seize. But the fact it goes away, and comes back, I would still check it out, but I agree in checking the continuity of the valve cover wiring.

 

The outer pins are the glow plugs and the center three pins are the injectors. The middle one is common to two injectors. The ones next to the middle pins are the individual injectors. There should be resistance is supposed to be between 2.5 and 3.5 ohms when measuring between the middle pin and one of the pins next to it.

The outside ones should have .6 ohms to the block. The most common failure is for one of the glow plug pins to burn up and then it burns the injector plug next to it.

If you end up replacing a harness for one side, save the good engine harness plug. You then can make an adapter that makes measuring resistance much easier.

 

I tested the pins and they tested good.

Would the IPR. Cause this roughness without any smoke?

 

Check your fuel pressure.

Give the IPR harness a check. Make sure the tin nut isn't loose. Oil level OK?

 

What is the proper way to check fuel prsseure? Any way to test the IPR?

 

Ok guys some new info I need your help with.

I felt like the problem is on the drivers side so I replace the valve cover gasket last night. Went out this morning and got her started. Nothing different; still hard to start and runs rough. Checked the fuel pressure and it's at 35-40 psi.

Well while I was standing there in wonder, I decided to pull the valve cover connections and see what happens. On the passenger side the truck dies each time I pulled one of the plugs. On the drivers side, the side I feel is the problem and the side I just replaced the valve cover gasket, nothing. Nothing changed. They are both pulled and the truck is still running the same as when they are plugged in.

So I am narrowing it down the best I can. The problem is on the drivers side. I'm thinking electrical. Maybe a fuse or a relay that controls that side. Anyone out there that can point me in the direction to look for something like that?

 

The idm has that side shut down for some reason. Possible its not working or maybe you have some injector problem. Be nice to see if there are any codes, and run a buzz test on the injectors.

 

No codes. I am not sure how to run a buzz test.