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What am I missing ?

X

xeonx2

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Location
Tennessee
We had a 94 Chevy 3500, 6.5 auto towed into the shop for a no start condition. Customer has a friend install new lp, sock and filter. also new gp controller and glow plugs. Have 5 psi and 1 pint of fuel in 10 seconds to the i.p. key on and while cranking... however no fuel to the injectors. I have cranked and cranked, checked all grounds, fuel shutoff solonoid and all are good and or working. I do have a code #25 app 2 circuit high, but i dont believe that would cause no fuel to the injectors. Any and all help / suggestions would be appreciated
 
Forgot to say we had ip sent to local pump shop. They tested it and said it was worn out but probably not the issue. We elected to get a new pump which comes with new module, sensors and switches. I still have no fuel to injectors. Plenty in but nothing out
 
Power to the ECM? there is 2 separate power supplies/circuits that power the ecm. Ignition switch is suspect also. Do I need to ask if ALL the grounds are squeeky clean? Does it have the filter[electrical interference plugged into the optical sensor on top of the ip] harness still?
 
I have removed and cleaned all grounds. As for the filter, I dont see anything on the plug end or on the ip end. Which would it be on. Is it across 2 wires ?
 
The "filter" he's talking about is a short harness, maybe 6" long from plug to plug. One end of it plugs in to the wiring harness going to the IP and the other end of this 6" filter harness plugs into the top of the IP.

Here's a pic of what he's talking about.
 

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It has a 6 inch or so inline harness that plugs into the pmd, nothing on top to the optical sensor
 
After looking at your picture I can see that is a 6 connector for the top of the ip at the optical sensor Mine has no jumper wire or filter harness there. The connector comes right out of the loom and to the sensor
 
If you are able to retrieve codes and connect the scanner to the PCM then it is powered. I wrote some no-start info at the end of this recommended mnx/mod list.

Did you use a different PMD or if there is some extra cable between the IP harness and the PMD eliminate it. Make sure the ground wire from the harness is still on top of the IP or at least well grounded.

My guess would be the PMD or the FSOL fuse under the steering column
 

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  • Mnx&Mods info.pdf
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I have fantastic grounds. I am able to interface with pcm and rear all data. I pulled the intake off before i went home and plan to pin out the ip. I also took filter housing apart to make sure no gunk or screen stoppage. Will my ip fire fuel to the injectors if the crank sensor is open. It's not shorted or i would think i'd see it on the codes and if i detach the 6 pin os harness what does the pcm rely upon for firing reference, Crank Sensor ? I also thought if i disconnect the os, that the pump would still send fuel to the injectors, just timed shitty.. Any and all info appreciated
 
Buddy I'm sorry i did not answer your question
2 nd new pump and pmd
No extra cable
Great groung on top of ip
All fuses good and power tesing ok through fuse
Took tghe pintle out of the sos
 
Did you make sure there is fuel to the IP or out the drain valve? The last ditch screen in the filter manager can clog and prevent fuel flow to the IP even if there is pressure out the drain which is prefiltration.

Might try to undo the fuel return line and crank it, which will show if its passing fuel and make sure the return path is not the problem.

Then there is the tests on the PMD harness you can do both with it disconnected and with it connected to see if you are getting all the right signals to and from it.
 
I ran through Buddy's no start diagnostic test and I have no a/c voltage from pmd connector b when cranking. All my other voltages are right on specs. I ohm tested b to f and have .5 ohms resistance. as per testing I am going to try a new PMD
 
No PMD output will certainly prevent any fuel to the injectors. That test on pin B must be done with the PMD all plugged in, because it is the PMD output. That part is explained in the text. So if the PMD was not outputting anything, but has power and signal from the PCM then best thing would be a new one.
 
Yep, everything was all plugged in and all other voltages within cranking specs. We will see what happens
 
Ok.... finally got new pump and now have a/c voltage from pin b and pump ground. But still no high pressure fuel from rear of pump. I have to be missing something. I have good supply and return is clean. Any Ideas ?
 
What is the AC voltage measurement on that PMD output? If its between 1.0 and 1.5VAC then it should work. Then you can do all the other things like unplugging the CPS and what not. How did you position the new IP, is it similar to the picture on the second page of that file I posted? Did you slide the IP's dowel into the eliptical hole of the timing gear?
 
ac voltage is 1.2 to 1.4 while cranking, unplugged cps, even installed a new one. The position of the ip is very similar and the pin is in the eliptical hole. But still no hi pressure fuel from rear of pump
 
If you have signal going to the IP, and no fuel coming out, then must be something wrong with the IP. Like the fuel/engine shutoff solenoid, which is the cylinder sticking up out of the IP. Also what model IP did you take off and what model IP did you put back on? If you took off a DS4-5068 and put a DS4-5521 on it would be hard to start. You can also check the PROM code inside the PCM to verify which model IP it should have. Its a 4 letter code starting with B on the PROM.

Is it cranking good? It needs to be 150rpm. Are you looking for fuel at the injector lines? It will be very little, normally the line would be full and when cranking it might spit out 30 cubic millimeters, which is like 3mmx3mmx3mm per injection, which is just a drop. Much less at idle.

Also, is your fuel pressure at the IP inlet or at the drain valve? There are a couple restrictions inside the filter manager between the inlet and the drain, that could block fuel flow.

There are other reasons it may not start. Such as glow plugs not working.
 
sound like a tuff one, sometimes I like a challenge other times I wish it onto others!! I hope you get her figured out and let us know what it is even if its dumb!
 
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