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Discussion Starter #1
Hey stoneage I had my '94 devilles's fuel preasure checked today and it was 30psi the service manual my brother has says it should be between 9psi and 13psi,so it looks like its pushing way to much preasure out. The mechanic says it looks like my fuel preasure regulator is bad and will need to be replaced. This is good news in a morbid way as we were thinking it was my fuel pump. When I told the mechanic how it acted up when it dropped below a half a tank of fuel he said that an FPR could cause this,could it stoneage? Should I sitll be looking at my fuel pump as the culprit or should I just change my FPR and go from there? Thanks for any help stoneage on this issue.
 

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Re: Stoneage_caddy I had my car's fuel preasure checked today,have a couple of questions

megatron said:
Hey stoneage I had my '94 devilles's fuel preasure checked today and it was 30psi the service manual my brother has says it should be between 9psi and 13psi,so it looks like its pushing way to much preasure out. The mechanic says it looks like my fuel preasure regulator is bad and will need to be replaced. This is good news in a morbid way as we were thinking it was my fuel pump. When I told the mechanic how it acted up when it dropped below a half a tank of fuel he said that an FPR could cause this,could it stoneage? Should I sitll be looking at my fuel pump as the culprit or should I just change my FPR and go from there? Thanks for any help stoneage on this issue.
No the fuel pressure should be between 30 psi and 44 psi depends on teh car but 9 13 is too low that might be the standing pressure or something but once the pump is on the pressure should be about 35 or so.

What are the problems you are having?

If your pump is whining or making any noises and you car acts wierd when your gas tank is low on gas then the pump is bad but if you have hard starting in the morning then that can be your fuel regulator.

let us know what is the problem your having I think both problems are usually around the same price look for the pump on ebay the are much cheaper than dealer price of over $250 i bought a new pump for $150 for a 2000 suburban and autozone pumps were $250+ dealer would've probably been $300+
 

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Re: Stoneage_caddy I had my car's fuel preasure checked today,have a couple of questions

First....never talk to that so called "mechanic" again. Any fool could tell you this is a multi port system, especially if the were hooking up a gauge to a FUEL RAIL and not a FUEL LINE to a TBi unit. Multi port pressures range from about 30psi on up. On my 91 deville which is esentially the same 4.9, it calls for 32-38 psi engine running. Of course you can check the regulator for function by pulling its vacuum line at idle and see if the pressure goes up and it it is leaking or not. FYI TBi systems run arround 9-13 psi.


-The Cadillac Rancher
 

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1989 Sedan DeVille is now just a fond memory ....
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ocjmakaveli said:
No the fuel pressure should be between 30 psi and 44 psi depends on teh car but 9 13 is too low that might be the standing pressure or something but once the pump is on the pressure should be about 35 or so.

What are the problems you are having?

If your pump is whining or making any noises and you car acts wierd when your gas tank is low on gas then the pump is bad but if you have hard starting in the morning then that can be your fuel pump.

let us know what is the problem your having I think both problems are usually around the same price look for the pump on ebay the are much cheaper than dealer price of over $250 i bought a new pump for $150 for a 2000 suburban and autozone pumps were $250+ dealer would've probably been $300+
:yeah:
A very wise man suggested to aquire a fuel pressure gage, attach it to a length of hose (36"?) with a fitting to attach it to the schrader vavle on your fuel rail, long enough hose to tape the gage to the windshield so that it can be observed by the driver while the car is in operation.

The pressure should be recorded while in various modes of operation to determine if the system is getting adequate pressure, Idle, acceleration, crusing, etc.

This is the best way to verify that the pump is in good working order.
 

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Discussion Starter #5
ocjmakaveli my car runs fine until it gets below half a tank of gas and then it idles really ruff and stutters and surges under acceleration. It also want to stall at idle sometimes it'll run really hard like its running out of gas or something. And the pump kicks on fine and dosen't make any weird sounds or any whining sounds either runs quiet even.
 

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Re: Stoneage_caddy I had my car's fuel preasure checked today,have a couple of questions

when it runs rough below half a tank , or in otherwords whent he fuel tank deterimnes how the engine runs you need to pull the tank and the fuel pump and find out whats going on .....really , to most anyone it makes sense that if it depends on how much fuel is in it as to how it run that the problem is int he tank

find a real mechanic , and get everything will work out fine ....

sounds to me like a sediment issue or the fuel pump overheating when its low on fuel ....happens when they get old ...

have you run the car OUT of gas yet ? try to run the whole tank dry before doing anything ...throw some "heet"(an additive) in it too .....lets hope your full of water first ....i doubt it but thats cheaper than dropping the tank ....
 

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Re: Stoneage_caddy I had my car's fuel preasure checked today,have a couple of questions

I'm leaning towards the fuel pump because the pump is more likely to act differently when the gas tank is below half and the lower it gets the more it will act up.

The fuel pressure regulator has given me different problems like hard starting or fast idling etc.



I also noticed that the pumps vary a lot depending on whether what letters your pump has stamped on it.

if your pump has ept or epw then its about $100 off rockauto and if its epv then its over $220

Let us know what you decide to fix and what happens afterwards.

If it was my money/car I'd go for the pump not because its cheaper but it's most likely the problem I would really think the regulator would show problems at all times.

Be cautious of shops especially the dealer I had a problem a couple years ago exactly like yours and I spent about $800 with false diagnoses from various shops and in the end it was the pump which I only figured out it was after i decided to give it a thorough check up myself.

On the suburban that was giving us problems whenever the tank would get below 1/4 mind you it was a big tank it would start to stumble really struggle to stay on the motor just felt like it wanted to shut off. It would set off an engine code that cylinder 6and 8 were running lean this lead to many false diagnoses but in the end it was the pump so if you get these problems then replace the pump.
 

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Re: Stoneage_caddy I had my car's fuel press checked today,have a couple of questions

First off tell your mechanic friend he either needs to go back to school. Or quit working on cars all together. I actually got told by one mechanic I needed to replace the speedometer cable in my car. He said he could fit me in this afternoon and it would only be about $200. After I stopped laughing at him and told him he was crazy because my car uses an electric VSS I left. I brought it in to him for a simple CV joint.

Now back to your FP and FPR or FPG stuff.

You can always just cheat and mount on permanently on the fuel rail. Please excuse the really messy engine bay. This was shortly after we got the motor in the car and were more worried about having it run right than look nice.




You can go to your local industrial supply store and get the adapters, and oil filled gauge and elbow for around 20 bucks. Just make sure to get one rated for a max of 60lbs. Makes it easier to tell a few pounds difference.

Someone on here posted the P# for an adjustable regulator which is a really nice addition when you have a gauge and can see how much you are changing things. During the winter you can run a little higher fuel pressure due to the extra density in the air.
 

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Discussion Starter #9
Re: Stoneage_caddy I had my car's fuel preasure checked today,have a couple of questions

Stoneage its never been out of fuel because I've never let it get that low cause it don't run right. I was thinking of tring to run it down and seeing what happens,stoneage will I damage my injectors or engine by driving on this fuel pump? Also which pump do I need a pump stamp epv epw or ept,and is there any way to know which one it is without pulling it out of the tank? Last thing is do I have to replace the sending unit or can I keep the old one with a new pump being it works fine?
 

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Re: Stoneage_caddy about my fuel pump issue?

There are lots of additives that you can use to help eliminate water in your tank. I would pick one and try it in a couple of full tanks of gas. Drive it untill at least 1/4 tank with both applications and see if you can tell any improvement. I don't think the injectors will be harmed with this proceedure, they may be improve with some cleaning.

If you don't have an OEM manual you need to get one. You can get one from Ebay (maybe) or for sure at www.helminc.com for around $110.

Which fuel pump do you need? You can find out by phone, call a good reputable parts store (I like Napa here, they know their stuff) or call any GM dealer parts counter. They should be able to properly identify your car and the pump that's right for it. Just a few phone calls should do it.

I replaced the fuel pump in my Mustang and kept the old sending unit. It works OK but I think I bumped it and knocked it out of adjustment. If your sending unit is working now it should work with the new pump. Just be very careful how you take the pump out and put the new one in.
 

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Re: Stoneage_caddy about my fuel pump issue?

Thanks kev will do I'am also going to run my tank down and try adding a fuel additive as it could be water or some other crud in my tank as stoneage suggested. It certainly can't hurt to try this before replacing the pump and if water or some other crap in my tank is the the issue alot cheaper to,I'll report back with my findings.
 

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Re: Stoneage_caddy about my fuel pump issue?

put "heet" in it , its in a yellow bottle at the parts store , follow the directions and run the car without filling it up till it stops running ....then get the jerry can of gas you put in the trunk and fill the tank and get to a gas station ....

fuel floats on top of water , or anything water based ...
 

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Re: Stoneage_caddy I had my car's fuel preasure checked today,have a couple of questions

Ok will do I might get lucky here stoneage it may not be my fuel pump if this thing with the heat dosen't work then off comes the tank. Also stoneage I was thinking beside the fuel pump I was going to check the fuel pump strainer,the sock that is part of the hose and anything else that may be casuing this while my tank is dropped. Stoneage when you said gas floats on top of water is thsi what could be happening here? Could the pump be sucking water when the tanks hits the half point mark?
 

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Re: Stoneage_caddy I had my car's fuel preasure checked today,have a couple of questions

its a possiblity , i mean anythings possible ...thats why i say to try this because its the cheapset thing to try right now ....it would be pretty damned rare to have THAT much water , but lets rule it out to be safe
 

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Re: Stoneage_caddy I had my car's fuel preasure checked today,have a couple of questions

Ok stoneage I am doing the heet thing and it acting the same I'am in the process of running to empty to see what happens. I also got under my car today and tried to check the wireing harness where the fuel tank is for a tag to try and see what my pump might be stamped ept,epw or epv. Do you know of anyway to check for this besides pulling the pump from the tank? I called the gm parts dealer and the cadillac dealer and they coulden't tell me for sure,stoneage is there any way to know what fuel pump I have w/o pulling it out of the tank?
 

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Re: Stoneage_caddy I had my car's fuel preasure checked today,have a couple of questions

most likely not, if they cant get you a part from the vin number ....its always best to have the old pump in your hands when you go in for parts anyway to ensure you have the right one ...
 
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Re: Stoneage_caddy I had my car's fuel preasure checked today,have a couple of questions

Hello all, my new 76 seville won't start. (new to me). I thought it was one of the fuel pumps, so I brought a gauge kit and tested it while I attempted to start it. Well it didn't start but it did read about 38 psi. Any advice on where I could check next.:suspense: :suspense: :suspense:
 

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Re: Stoneage_caddy I had my car's fuel preasure checked today,have a couple of questions

38s pretty damed good ...you sure its a fuel issue ? try spraying carb cleaner into the throttle body while trying to crank , see if that changes anything (you probably tried this i just have to say it)
 
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Re: Stoneage_caddy I had my car's fuel preasure checked today,have a couple of questions

I will try it, I had thought about it. How Often due the EFI computors cause problems, and how do I check it?
 
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