99 7.3 losing ICP on hard accel

Buddy_M · February 8, 2010

OK guys.. I'm getting frustrated because this is my own truck. I want to get a little insight and second thoughts before it drives me crazy and I do something stupid with it anyway.

Upon hard acceleration I'm losing ICP dropping to 300-500psi and the IPR is maxing out at 65. ICPV is correlating with the 300-500psi ICP. I have triggered the IPR with 12v and cranked the engine to check for oil leaks under the covers and there are none, ICP builds to ~3800 and cuts out at the relief pressure and holds fairly well with minimal drop.

After a cold engine start, it will build ICP up to 1000-1500 and IPR is approx ~20% holding WOT in the shop, but once I accelerate going down the road it will drop out and I can barely limp it back to the shop. I can't even get it to run without holding the accelerator down now, and if i let off it dies, so i can't run any contrib tests, but I have gotten failures with 3 & 8 prior a long time ago, but never any drivability probs or noticeable miss, so I have never replaced those injectors or looked at them when I got those codes. I have recently replaced all the injector o-rings and an injector cup as well, and the oil is good, just changed about 300 miles ago, and fuel pressure is good. Since the HPOP builds and holds 3800 ICP when triggering the IPR, is it possible I have an injector or 2 sticking open releasing oil causing my ICP to drop and the IPR to max out?

Fordracer · February 9, 2010

What is your base engine oil pressure when this happens? It sounds like you might be loosing oil pressure to feed the high pressure pump.

batmantech · February 9, 2010

FYI Also check out this past post.Mine was a high press. pump

http://www.forddoctorsdts.com/forums/ubbthreads.php?ubb=showflat&Number=24357#Post24357

Alex Bruene · February 9, 2010

Silly question... But have you checked to see if the nut and hat are still on the IPR? I've seen them come off and the IPR will slide in and out on accel and decel causing weird issues.

Keith Browning · February 9, 2010

Silly question... But have you checked to see if the nut and hat are still on the IPR? I've seen them come off and the IPR will slide in and out on accel and decel causing weird issues.

As silly as that sounds I have seen it couple of times. If I recall it was really strange because it only happened under hard accel. I started our looking for a harness problem thinking that the engine torquing and pulling the harness was causing it. Then I discovered the said nut and spacer in the valley and the IPR field sliding freely on the valve.

Buddy_M · February 9, 2010

Nope, the tinnerman nut is on and secure, that is one of the things that had crossed my mind as I have seen that once before. I got the engine up to temp and power braked it and got it to act up in the bay and drop ICP and max IPR. I also tried grounding out the IPR signal wire while running for shits & grins, and it made no change in ICP, but tomorrow comes a new day and a fresh look at it. Just got home from our dart league and feeling just a lil Posted Image

Bruce Amacker · February 9, 2010

I'm with the "check the LPOP" crowd....

Posted Image

ktmlew · February 9, 2010

It being a 99 I would look closely at the wiring harness in the LH engine lift bracket & LH shock tower area...but the other suggestions are valid also.

Buddy_M · February 10, 2010

I got a little bit of time to mess with my truck today, oil pressure hot at idle was around 15psi, and at WOT it was at 50psi, both above min spec at least. Wiring is ok at the left valve cover & shock tower, that was one of the first checks since I have seen them wear there before. Won't be able to get to it much more for a few days, unless I stay late and tinker with it, but I'm getting to the point I have another engine sittin in the corner, either swapping parts around, or swapping engines.

LARRY BRUDZYNSKI · February 10, 2010

Changed the oil pan lately? What about the pickup? To many have had a bad pickup gasket or blockage.

jaysonfordtech · February 11, 2010

cracked pickup tube perhaps, also I would be looking to deadhead the pump and see max pressure.

Buddy_M · February 12, 2010

Deadheading the pump, and isolating and pressuring up each bank pressured up to and held 3800psi. This afternoon, I replaced the HPOP & IPR for shits & grins since I had an extra engine, and it runs & drives fine now, IPR is back down to where it should be and there are no other problems. Maybe someday when I get bored I'll tear the old HPOP apart and see if I can see a problem with it that caused my headache.

Buddy

Mbl35 · May 16, 2010

I had the same thing waiting to greet me when i came in to work thursday eve. You coud barley get this thing up to 35mph and the check engine lt. comes on at hard accel. I really coud not watch my icp and ipr pids because im driving in traffic. It starts fine cold and hot though. You clear the codes and drive it on accel like 1 block and right away ckek engine lt-p1211 and 1212. I bring it in and first i drop the tank(oil just changed and level fine)just to inspect for a blockage in the sending unit-just to cover all bases. The filters were blocked. I change out the sending unit, pump and fuel filter also remove and install new oil into the hpop reservoir. I drive it and same thing after 1 block. Right back into shop, i rnr hpop and ipr. I drive it 3 miles and runs like new, eec test pass. I don't have a fuel pressure testing adapter for this and i see more fuel related failure than pump failures on 7.3 so thats why i hit the fuel system first despite the icp codes. Anyway it was justified for me to change the sending unit because those filters were plugged.

Jim Warman · May 17, 2010

Remove and install new oil in the HPOP reservoir? Cool....

Mbl35 · May 18, 2010

Yea, i siphoned out the old crappy oil up in there and put in fresh new oil-could not hurt. Plus i wanted to cover all bases before i put the only 7.3 hp pump we got in stock rite now.