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sprinkles08, ASE Certified Technician
Category: Mercedes
Satisfied Customers: 23109
Experience:  ASE Master and Advanced level certified. Factory trained with 17 years dealership experience
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Dixon here just searching how to test a fuel regulator on a

Customer Question

hi Dixon here just searching how to test a fuel regulator on a high pressure pump. long story short. gasoline added to diesel car and now no starty. drained system completely. Now have fuel to high pressure pump and not through to rails. only code in car is throttle actuator bank one p0638
Submitted: 1 year ago.
Category: Mercedes
Expert:  sprinkles08 replied 1 year ago.

Hello and welcome to JustAnswer!

You may have a handful of things going on. The no start may be from residual gas or it's possible that damage to the fuel system was done from the gas. Usually the engine will stop running before catastrophic damage is done though.

What was done to drain the contaminated fuel out?

Customer: replied 1 year ago.
Hi thanks for getting back to me. I am actually the second shop to work on the car. Some suspicious things have happened. The first shop drained it. I spoke with them regarding the drain procedure and it sounds legit. The high pressure pump was removed. In tank pump was removed. Lines and rails all flushed out, tank pumped out.
Customer: replied 1 year ago.
New fuel added. Then insurance stopped work order. Sooo. I got vehicle from a customer that bought it at auction. He brought to me and I found no gear on pump and it was loose. I ordered a gear put it on. Got fuel to flow into pump and through return. Tested solenoid on pump and it actuated and with it removed fuel flows through its voided space. So now I have fuel bubbles only at high pressure output. No leaks on fuel line to pump.
Customer: replied 1 year ago.
I phoned the shop in Calgary to my surprise they happen to have a high pressure pump with a gear for 400 dollars. Weird! Wonder why.
Expert:  sprinkles08 replied 1 year ago.

If you do have proper fuel to the high pressure pump and it's output is low or non existent then the failure does have to be internal in the pump, assuming there isn't a mechanical issue preventing it from turning.

The pump they're willing to sell for $400 must be used as a factory replacement runs just under $1,700 before tax.

Customer: replied 1 year ago.
Ha ha I think the mister you pump in Calgary is off of this car.
Customer: replied 1 year ago.
Mystery pump
Expert:  sprinkles08 replied 1 year ago.

It's very possible. Other than having to stop work abruptly in the process of putting the pump back on, I don't know why you would have gotten it with the gear removed. They may have installed a known bad pump on the car to try to get the insurance to pay for a new pump for another vehicle or something of that nature.