I tested my fuel pressure because every once in a while I can smell fuel in the cab, I also recently blew a head gasket and had alot of carbon build up in the engine, this is on my 95 blazer

The pressure with pump running (engine off) was 62 psi and it droppen down to 58 psi as soon as the pump stopped, it held 58ps for 3 min,

Should I be concerned about the slight leak down?

time elapsed (minits) pressure
4 57
5 56
6 56
7 56
8 55.5
9 55
10 55
11 55
12 55
13 55
14 55
15 54
16 54
17 54
18 54
19 54
20 53.5
25 52
30 52
35 50
40 50
50 49
60 49


Thanks in advance for your input....

BTW My nickname (Zombiewoof) comes from the title of a Frank Zappa song I like

 

The pressure shouldnt drop more then 3-5 PSI

 

A slow leak down like this could be caused by the 'nut kit' (internal lines), the fuel pressure regulator, or the check valve in the fuel pump itself. It doesn't sound like an excessive leak...

 

the pump was new about a year ago...although I do have the dancing fuel guage syndrome, I noticed a verry slight washing on the regulator side when I had the upper intake off,,,I think Ill just go ahead and replace it,,,Its funny how I had to spend 70$ to diagnose a 40$ part...hehe..oh well at least i can segrigate a fuel problem when needed...thanks for the replies

PS Kyle...the pressure tester I made at work would have been good...I found this big 100psi liquid filled sour gas gage...had a bleeder valve set up with a drain hose, and was using a pressure line from a grease gun...it looked like a store bought unit...But I couldnt find anything to conect to the schrader valve...hehe people looked at me like i had rocks in my head when I was trying to explain what i needed it all for (the conector)...

 

This is so great that somebody posted this, because my '96 has also been having a fuel pressure problem lately. I just bought a fuel filter today and plan to get a regulator tomorrow, once I find a parts store that actually has one in stock.

I don't have a gauge to test it with, but I figure it can't hurt to replace both anyway. The filter hasn't been replaced during the three years we've had the truck, and the regulator has probably never been replaced ever.

The problem I'm having is that it never starts right up. It takes at least 2-3 attempts. The starter sounds fine, and I know it's not spark, because the plugs, wires, and distributor are all new and working fine. Hopefully replacing the filter and regulator will resolve theproblem, 'cause if not, it will make me think the pump itself is dying.

Anybody else have any thoughts on this?

 

I think your in kind of the same situation I was in...as in being..your not really going to know whats going on with it unless you get the guage on it....I hope you can solve your problem with the regulator and not have to get a new pump...But I did read a previous post that said the initial higher pressure is needed for starting...

 

Okay, because it's good to know that I'm on the right track. I ran a search and found another really helpful thread about that issue here: Click Clicky

Thanks!

 

On my 95 blazer if I want to replace the fuel pressure regulator (CMFI system) It apears at though I would have to replace the whole CMFI assembly....is this correct? Because Rock auto lists a pressure regulator but my manual says the regulator is part of the whole assembly....In wich case a pressure regulator is gonna run me somewhere in the neighborhood of 400 - 450 bucks....OUCH!!

 

It is replacable, however it isn't an easy job. The Lindertech repair kit replaces the stock regulator on the CPI with one used on the SCFI (96+) spiders. They have complete instructions for the change over as well. It will require removal of the spider which I would recommend that you replace the 'nut kit' (internal lines) as well.

You might want to check out the whole kit which includes a refurbished CPI spider with updated FPR, the 'nut kit', an upper plenum gasket, and a screened EGR gasket for $300. I have never heard anyone say anything bad about the parts received from Lindertech.

 

Thanks again Kyle, I just E-mailed them to see if they would ship the kit to Canada,..Before I decide to go this rout I suppose I should test to see if my leakdown is from the CPI unit or the pump damper, The only reason Im looking into this is that I noticed a small spot of washing in the upper intake when I was replacing my head gaskets...it was near the rear corner by the rear passenger side, I have had a slight missfire(more like a small stumble...not really noticable and never effected the idle rpms) for a long time also...I also had some oil in the upper --- I think that was form a bad pcv..
The upper intake is really in no way washed...its nice and dirty as you would expect it to be,,,all except for a small spot about 1/2 the size of a dime...Im wondering if the oil (real small amount) could have caused that clean spot??

I wish I had of taken a picture of it to post....But Thanks again for the info