Lost MPG after VE injector pump rebuild. I’ve had good experiences at NTG Racing up till now. Time to rebuild the injector pump so I took it to NTG Racing, it was leaking bad. I just ask for good mileage and no performance up grades. I was hoping that it might improve my MPG of 16. They sent the pump out to Omega for the rebuild. Got the truck back it seemed OK until I filled the tank and checked the mileage. Holy crap 12 MPG. I have never got that bad a mileage before. It was always around 16 MPG . Well took it back so they could figure it out. They gave it back to me after some adjustments to drive, wow now I could watch the fuel gauge move, 9 MPG. I took it back, they were stumped. They checked other components. “Everything checks out fine. “ Its got to be the injectors,” OK if that fixes it I’ll pay, if not I won’t pay for them. They didn’t change the injectors. They drove it and adjusted the fuel screw on the pump (per the rebuilder Omega) that brought it up to 10.5 MPG we’re not even back the 12 MPG I got at the first try. So is it the pump or is it the injectors? I removed the injectors and had then tested (Advanced Diesel) they tested OK, not the problem. As they had a little over 100,000 miles on them I had them rebuilt. Reinstall them and no change. NTG took the pump out and had it tested (Express diesel) a Bosch Certified center. The pump was taken apart and inspected. Not all the worn parts had been replaced. But still OK . Reassembled and ran on their test machine and readjusted to factory specs 1.25 then advanced to 1.45. Reinstalled ( with a dial indicator) in the truck and now I have it back. It seems ok, a little less power. Put some freeway mile on it and I got 12.65 MPG. Not the decent MPG I had before the rebuild All I want is my 16 MPG back. I’m losing 4 to 5 miles per gallon that adds up quick. What have they done to my truck? And they are still stumped. I still think it’s the timing. Joe said he doesn’t want to see the truck again. Now what?

1992 w250 LE auto 4" exhaust 16 cm gauges rebuilt ve pump & injectors 103,000 12mpg ?

 

Joe doesn't want to see the truck again, I think that I would have a "private" talk with Joe, then make a BBB complaint, see how he likes that. Did they install the pump back to the original timing mark on the case? You may want to advance the timing a bit, ie, push the pump toward the head and see what happens. You should definitely see more power...Mark

 

Getting any fuel in your oil? Could have buggerd the front pump seal. Just a stab in the dark.

 

Did they guarantee that it was your pump they sent out and got back? If not then there could be other pump issues. Strange that one component could cause that big of a swing in mileage.

 

Do you have any gauges, if so did the EGT change any from before?

Also has the fuel pin been turned any?

 

Adjust the valves.

 

Good point on it might be a different injector pump, you got back.
It might even be a NON intercooled injection pump.
The IC and NON I/C pumps have different injector pressures to go along with the different injector sizes, IIRC.

 

That was my train of thought exactly.

 

Thanks for the replys
No fuel in the oil
I was told that its my pump
Yes gauges egt about the same
Pump setting are stock, just the 1.25 to 1.45 advance
Valves adjusted

Searching for my MPG

Thanks Guys

 

Are you getting any smoke on acceleration? Is there any haze when you're idling? Are you 100% sure it's set to 1.45mm of lift?

 

Somehow, this seems almost impossible to me. I would think your EGT's would have had to go up.

It pretty much has to be an either NOT pump related change, or retarded timing (which might include low injection pressure or a stuck advance mechanism).

 

Retarded timing should make EGT's go up...

 

How would I check a stuck advance mechanism and where is it?
Thanks

 

A bad air temperature sensor, or wiring to the KSB....I had not thought of that. Just try unplugging the wire from the KSB, and drive the truck. You can also use a test light to check the power to the KSB. The wire should have 12V when you first start the truck, but after the motor warms up a bit, the air temp sensor should turn off the 12V and it should have no power at the connector.

 

Actually, if the KSB is stuck on, it should not affect mileage, or even slightly improve it. What you lose is low end grunt. The reason for the advance is to slightly increase idle speed when cold.

I vote for something basic wrong with the pump, either low injector pressure, or an internal timing problem. I think you'd have to rig up a scope with an accelerometer (microphone) on a fuel line and an index input from the CPS to prove it. Perhaps just comparing the accelerometer output (voltage) between a known good setup and the suspect one could discern poor injection event pressure or definition.

It would seem to me that with that poor mileage, you'd have to be making some smoke or haze. If the fuel were burning, EGT's would be high. If not, it has to go somewhere.