Still stumped over '94 PSD

[Tim the 2lman]

I bought this '94.5 no run and thought I'd simply wave the magical mechanical wand and have it runnning. Well no such luck. After a month and a half, It still isn't runnning and doesn't act like it wants to. I'm not getting sufficient oil pressure while cranking for the PCM to tell the IDM to come online. Getting 476psi and need min. of 500psi. Installed a good used HPOP from an '02 PSD did the mods to the front cover and installed '02 reservoir. Original pump gave me about 425psi. These numbers are with one oil line capped off and the other line terminated into an oil filled 0-4000psi guage. Crank speed is ok but not great. I've seen these things crank slower and still fire up though. I've got fuel pressure but I haven't put a guage on it to measure how much. I've tried unplugging the ICP but it still doesn't fire up. Anyone got ideas?

I am concerned that I may not be getting good voltage to the PCM while it cranks. Any idea what that voltage should be? The wire that attaches to the battery terminal and feeds the starter relay where everything is fed, gets mighty warm when the GP's are cycled on and it's cranking.

I've got to be over looking something very simple.

 

[BigRigTech]

Have you tried a code reader to see if any faults are active?
Are you sure the oil pressure isn't bypassing bad injector o-rings?
Is the tach/scanner reading cranking speed?
Have you tried another known good IDM or PCM?
Any signs of engine oil in the fuel bowl?



....Really, anything over 300psi will start to bring these things to life...cranking 200-300rpm should show you 500psi or close to it. ..I just went through a no start on my buddy's 97, took me 10hrs to fix it....Bad PCM....I had 500psi while cranking, 70psi of fuel pressure but no cranking rpm on the tach or the scanner. I tested the CPS wiring and ruled everything out by the process of elimination until he bit the bullet and bought a $600 PCM....Man was I happy when it started......The old PCM was so bad that it fell apart when I pulled it out. Me - I would go in a different direction, forget about huei pressures as what you have is ok and start looking at the electrical possibilities...Another PCM or IDM would be my first test. Also, flip the fuse box over and see if any wiring is green - I've seen some nasty stuff there....Another issue I've seen is the truck not starting in Park but it would in Nuetral - the range selector on the trans was bad.....A few things to think about for now.

 

[Mike]

Are you getting white smoke while cranking?

 

[Tim the 2lman]

Oh yeah, you reminded me. Yes I've tried another PCM same exact result. Pulled the IDM and slapped it into a '97 and it fired right up. Got a stick shift so selector not an issue. The diesel shop behind our shop told me that if the oil pressure is below 500psi while cranking, the injectors are disabled. Don't know what crank speed is. Tach operates while cranking telling me CPS is working.

Do the old mechanical pumps put out that kind of fuel pressure (70psi)?

Let me correct myself, I read 510psi on the guage both lines disconnected from the heads and terminated with a plug and guage. This is after the HPOP/reservoir and front cover mods. Before the mods the guage pressures were about 425psi with the old HPOP setup with about 399psi on the ICP. The readings in my first post are via scanner watching the ICP readings.

The only code set full time is IAT ckt high, because I don't have an IAT sensor. All other codes that come up from time to time, I induce during troubleshooting. Buzz test runs perfectly, if that helps.

 

[BigRigTech]

I read my HUEI pressure in the head with a 6000psi gauge, nothing disabled or plugged...I wanted to see what the injectors were seeing....I had no smoke as the PCM was not telling the IDM to fire the injectors. It can't hurt to verfiy solid power and grounds to the PCM and IDM. Another trick would be to disable the GP's and sniff it with ether will cranking, it will give you a little perking up while cranking and possibly more pressure to fire things up. I saw 70psi of fuel pressure while cranking the engine over on a gauge.

 

[Mike]

Are you getting white smoke while cranking?

???

 

[Tim the 2lman]

No Mike. No smoke at all. BigRigTech, I capped off the lines to help eliminate injector o-rings as the sole cause of this problem. I figured that if I wasn't seeing sufficient oil pressure with it capped off then I certainly wouldn't with it connected to the heads. Does that thinking seem reasonable? Most of the testing with the lines capped off have been done with the ICP disconnected as well so as to send the PCM into pre-programmed mode. I have verified all power inputs and grounds to the PCM although I haven't checked out the IDM for that. How did you get your guage on your fuel test port? Mine is so close to the engine hoist ring that I can't get my guage on it. I thought about getting an elbow and turning it out so I can get to it. Just haven't done it yet. I have tried a little ether. It just rattled like a bucket of loose bolts for a second but no start.

I'll have to check the IDM tommorow. Good stuff. keep it coming. I know there are some more things that I haven't thought of.

 

[jfinch]

Bet its your IPR. mine was broke down 5 months before i figured it out. took going to ford 2 times for a total of 3 weeks and two other mechanics to get it right. oh ya ford did nothing but take my money they suck at diag. but ya i had all the symptoms, changed the PCM, EBP, hell i damn near replace everything. check out my old posts on it and you will see. but ya IPR valve....Check it out.

 

[Tim the 2lman]

Thanks jfinch, that reminds me of another thing I've left out. Three different IPR's. One of them brand new as well. The '94-95.5 pumps require an IPR with the edge filter. One of those was the new one. The newly installed '02 pump does not have the edge filter in its IPR.

 

[mankypro]

This thing in a truck?

 

[Tim the 2lman]

Yes. '94 F350, CC, SRW, ZF-5, 2WD

 

[BigRigTech]

I took the shrader style fuel fitting out of the fuel bowl and put in a fitting to get my gauge hooked to it...It built to 70psi while cranking. Have you actually hooked a gauge to the HUEI rail in the head with the hoses hooked up? the pressure could be really low if the o-rings are bad. Have you tried un-plugging one plug from the VC at a time to see if it would start or smoke? Are you getting voltage to the IPR?

 

[Double-S-Diesel]

id say IPR, ya should build 2500psi + with the lines disconnected.
also check the wirtes going to the ipr, they sometimes melt

 

[Tim the 2lman]

Nope wires are good. I watch the signaling all the way to the PCM. They look the same from end to end. The IPR duty cycle at crank time is only 15%. I'm not sure but I think that only translates to something just over 500psi. I just noticed something else though.

I went out and cranked it over and watched the tach. It read maybe 150 to 250. Kind of hard to tell. However, when I watched the scanner while cranking, RPM's stayed at 0.

Has anyone watched their truck crank and not start with a scanner and seen RPM readings? Might I be dealing with a multiple problem scenario here like bad CPS and bad ICP.

 

[Tim the 2lman]

Well, I may have just answered my own question. I went back out, unplugged the CPS and cranked it. What do you know but the tach jumped up to the same exact place. Off to the parts store I go. Cross your fingers.