How to check bad fuel pressure regulator?

gorillajin · 10-13-2009, 06:58 PM

Hi,

Does anyone know absolute way to check a FPR?
I heard that if I can smell fuel from the vacuum hose connected to FPR, means bad. However, I want to know if there is another way to check.
I don't want to do any guess and keep changing wrong parts.
I have changed a fuel filter, OVP, plugs and wires due to cold starting issue.

Thanks.

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JSe420 · 10-13-2009, 10:45 PM

What you need is a vacuum hand pump with a gauge on it. Once you have your pump, hook it up to the fpr by simply connecting it with a small peice of rubber hose (but make sure its tight and doesnt leak) and see if it holds a vacuum. If it doesnt hold a vacuum then its bad.

gorillajin · 10-13-2009, 10:59 PM

Thank you for the reply.
Where can I get the tool? Can I rent it from some auto parts store?
If you have a picture of the tool, please let me know.

Or if it's that easy, should I just ask a mechanic to do it? I am sure it will be either free or $20...

Thanks.

appatula · 10-14-2009, 04:32 AM

http://www.harborfreight.com/cpi/cta...emnumber=39522

Very useful troubleshooting tool. So many things on these cars are vacuum actuated, including most of the climate control components, door locks etc.

Also a generic version:
http://www.harborfreight.com/cpi/cta...emnumber=92474

gorillajin · 10-14-2009, 12:42 PM

Thank you so much for the link. I will buy it today, and post here how is my FPR.

gorillajin · 10-14-2009, 02:41 PM

I got the tool, and tested the FPR.
It hold compression just fine. I guess FPR is ok.
Now what should I check?

As I said, changed OVP, fuel filter, spark plugs&wires, and FPR is fine.
Can this be ignition coil?

10-13-2009, 10:59 PM	#3
gorillajin Member Garage is empty, add now Join Date: Aug 2009 Posts: 151 Drives: 1994 e320 sedan	Thank you for the reply. Where can I get the tool? Can I rent it from some auto parts store? If you have a picture of the tool, please let me know. Or if it's that easy, should I just ask a mechanic to do it? I am sure it will be either free or $20... Thanks. Last edited by gorillajin; 10-13-2009 at 11:02 PM.

10-14-2009, 04:32 AM	#4
appatula MBWorld Fanatic! Garage is empty, add now Join Date: Feb 2007 Location: Connecticut, New Haven Posts: 1,294 Drives: 95' AMG SeeThreeSix	http://www.harborfreight.com/cpi/cta...emnumber=39522 Very useful troubleshooting tool. So many things on these cars are vacuum actuated, including most of the climate control components, door locks etc. Also a generic version: http://www.harborfreight.com/cpi/cta...emnumber=92474 __________________ \|_1st-1980 280CE=TOTALED_\|_2nd 1999 C280=TOTALED(rollover)_\|_Current 1986 300E 160K_\|_1995 AMG C36 145k_\| Visit RHW's, aka Rich's Website For More Pics!

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10-13-2009, 10:45 PM	#2
JSe420 Senior Member Garage is empty, add now Join Date: Apr 2009 Posts: 297 Drives: 1994 E420	What you need is a vacuum hand pump with a gauge on it. Once you have your pump, hook it up to the fpr by simply connecting it with a small peice of rubber hose (but make sure its tight and doesnt leak) and see if it holds a vacuum. If it doesnt hold a vacuum then its bad.

10-14-2009, 12:42 PM	#5
gorillajin Member Garage is empty, add now Join Date: Aug 2009 Posts: 151 Drives: 1994 e320 sedan	Thank you so much for the link. I will buy it today, and post here how is my FPR.

10-14-2009, 02:41 PM	#6
gorillajin Member Garage is empty, add now Join Date: Aug 2009 Posts: 151 Drives: 1994 e320 sedan	I got the tool, and tested the FPR. It hold compression just fine. I guess FPR is ok. Now what should I check? As I said, changed OVP, fuel filter, spark plugs&wires, and FPR is fine. Can this be ignition coil?

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