My saga continues.

After being convinced my IP was bad (see idles fine but dies when put in gear) I pulled it and installed a reman from a Bosch rebuilder.

I noticed right away while trying to prime the fuel system that the FASS would only do the little half second bump and would not continue to run for the 20-30 seconds after a starter bump.

It will do this every time even after cranking, no FASS 30 second cycle just a half second run.

I checked the FASS relay, all good. I hot wired the connector and the FASS runs. This ran just fine prior to IP change out.

So, now I have managed to get fuel to the IP and injectors #1, #3 and #4. There seems to be good fuel there but no start. Nadda.

Maybe the IP was good all along and I have some other problem and why doesn't my FASS operate the same? Does the IP normally run during cranking?

Beyond frustrated man

Taz

 

Any codes? It wouldn't hurt to bleed the other lines as well.
With fuel it should at least try to start unless the timing is way off.

How warm is your engine when you try to start it. I am south of you and it is stupid cold outside. Hard to start even with six fully primed cylinders.

 

Any VP44 gurus around?

I have a theory here and need to prove/disprove it before going further.

As posted previously, after a replacement VP was installed I notice the FASS not doing the 30 second cycle, just the pre-start bump.

I checked for codes with a reader that was a bit more robust than mine and see P1688, yea I know, and P1689 "No Communication Between ECM & Injection Pump Module" Remember, this is a "new" VP reman.

My theory here is the VP is not for my application. It is unable to establish comms with the ECM and therefor telling the FASS stop fueling or not engage the 30 second cycle after the starter crank/bump. Is this a possibility??

The p1688 code is hopefully comming up because of the 1689 so the next question is that possible?

I had erased all codes prior to doing this job. Did not have a very good reader at the time so I'm not sure what was there in the first place. I did erase all of these last night and tried to start, no go and noticed the FASS was still not doing it's cycle. I did not see the CEL come on again and there were no codes set after a 20 second crank.

The next burning question is if my original VP went south and set P1688/1689 does the ECM need to be reset and not just cleared in order to acknowledge the replacement VP44?

Sorry for the long detailed post. I'm outside in the snow and wind after work trying to get my ride back on the road.

Much appreciated,

Taz

 

Should not need either for a successful restart.

Since you suspect the wrong pump..... see if you can read the last two digits on the Product code # for the VP-44, on the plate on the pump.
Will be either a 047050627 (Standard Output) or a 047050628 (High Output).
The HO engines run well on either pump but I think the SO pump (#27) has to be used on any SO engine....
like yours or mine.

RJ

 

I was thinkin the SO pump would work on an HO motor? Maybe I heard wrong, but thats what I was thinkin

 

check on blue chip,s web site he has a nice vp44 troubleshooting chart that may help you out.

 

With code P1689, check the fuel pump relay in the power box under the hood. Swap it out with the horn relay and see if it starts.

 

Thanks Rual,

Great suggestion but fuel system relay checks out fine.

I did some more bleeding and observation tonight. #1 and #3 seem to have good fuel that pulses on crank as you would expect.

The bad news is although I did not activate the CEL, P1688 has returned. Could this be so on a fresh reman? Is there any chance at all that the ECM is pooching the new pump electronics??

Got to know before I engage the rebuilder or get another pump yikes

Taz

 

Works well! I believe that's what I said above.

RJ

 

Negative. I don't have a VP anywhere near my truck, and it still will run for 30 seconds if I bump the starter.

 

I had a similar issue, disconnect the battery for a while to rest the computer.

 

u can use either pump on so motor but can only use ho pump on ho motor.....your original vp is prob still good and its ecm prob., id bypass the ecm to fass power connection and wire an ignition hot relay to it. cheap, fast easy fix. I notice when its cold out and batt voltage is very low due to grid heater draw my lift pump will not stay running either, but my relayed pusher allways runs with no prob. From what i understand the so pump is more desireable, supposed to be capable of more fueling..

 

That is incorrect! Think you have it backwards!
I have driven a 6 speed (HO engine) with an SO VP-44.... know of two others that went with SO pumps to get higher HP.

RJ

 

...Why yes you did, haha. I read it wrong, wasn't tryin to question ya, its just that I'm in the market for a new VP and wanted to make sure.

 

Still at it. I disconnected the new reman IP and cranked over. My lift pump now cycles as it should. This IP is definitely influencing something in the ECM........