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95mc
08-28-2007, 08:26 PM
95 prostar 275 hp tbi...I have to replace fuel pump and dealer told me that existing fuel pump (original) is a low pressure (13-15 psi) and all that is available is a high pressure (38-40 psi). After replacing fuel pump he warned me that because of the increased pressure TBI regulator in Throttle body will allow more fuel and engine will idle rough and use more fuel. Has anyone else had this problem ? ? ? I will be replacing fuel pump in the next couple of days.:confused:

André
08-28-2007, 08:32 PM
95 prostar 275 hp tbi...I have to replace fuel pump and dealer told me that existing fuel pump (original) is a low pressure (13-15 psi) and all that is available is a high pressure (38-40 psi). After replacing fuel pump he warned me that because of the increased pressure TBI regulator in Throttle body will allow more fuel and engine will idle rough and use more fuel. Has anyone else had this problem ? ? ? I will be replacing fuel pump in the next couple of days.:confused:
You mean the dealer knowingly sold you the wrong pump for your engine???:rolleyes:
Skidim has the right one.In stock,I'm pretty sure!

95mc
08-28-2007, 08:38 PM
no dealer and skidim only carry high pressure pump...Low pressure is not available!

ride
08-29-2007, 12:30 AM
You mean the dealer knowingly sold you the wrong pump for your engine???:rolleyes:


Yea, I'm with Andre on that one...

no dealer and skidim only carry high pressure pump...Low pressure is not available!

My understanding is the part is no longer current and has been discontinued in both GM and Ford's system (they no longer even have a part no. for them), HOWEVER, they ARE made as an aftermarket part (again, from what I understand). If skidim doesn't have it, try NAPA. While in the middle of nowhere, they found the dealer-stocked part for me at a $160 savings off of dealer price quote to overnight me one. You'll need the Part # off of the pump body, or ideally the pump itself as the guy that helped me found it in his book listing the pics/images, thus the visual reference helped confirm we had the right one.

Obviously the right part is your best fix. If you can't find one, you might have an option with your fuel pressure regulator. Storm861triple or JimN might chime in to help you out there.
GL

Storm861triple
09-07-2007, 04:39 PM
I can help w/this one...and I don't even know which pump is right or not! But is doesn't matter.


The problem is w/the basic statement that the dealer made...
"all that is available is a high pressure (38-40 psi)....he warned me that...because of the increased pressure TBI regulator in Throttle body will allow more fuel and engine will idle rough and use more fuel.

I'd have to ask the dealer what the snuck (I can't believe "double-u, Tee, Eff" is censored!) he's talking about! The FUEL PUMP has absolutely zero control over the fuel pressure. All the pump can do is move fuel. The pressure, comes from a resistance to flow, and that is caused by the Fuel Pressure Regulator located in the TBI assembly. The FPR is simply a valve w/a diaphram that has a spring behind it. The fuel pump pushes fuel to the TBI unit, past the injectors, and the "path ends" at that valve in the FPR. The pump is still pumping though and since there is no where for the fuel to go (resistance to flow) the pressure in the system rises. When the pressure reaches a point high enough to overcome the spring behind the diaphram, the valve opens, and fuel flows past it, and back to tank.

If your fuel pump is faulty, and you're replacing THAT, what does the FPR in the TBI unit have to do with anything? The fact is, you could put the fuel pump in your boat from a Top Fuel Dragster, and your stock FPR will govern your fuel pressure to the stock setting, by dumping excess back to tank when the pressure in the system (set by the FPR) is reached. In short, you virtually can't pump too much fuel and flood the engine if the FPR is functioning as designed.

JDK
09-07-2007, 06:07 PM
If skidim doesn't have it, try NAPA. While in the middle of nowhere, they found the dealer-stocked part for me at a $160 savings off of dealer price quote to overnight me one. You'll need the Part # off of the pump body, or ideally the pump itself as the guy that helped me found it in his book listing the pics/images, thus the visual reference helped confirm we had the right one.


Would you happen to have the pn. of this replacement you purchased from NAPA??? I've been looking for a spare for years, and nobody can seem to come up with it (to get this # on my pump, I've got to remove it)

Engine Nut
09-07-2007, 08:33 PM
I can help w/this one...and I don't even know which pump is right or not! But is doesn't matter.


The problem is w/the basic statement that the dealer made...
"all that is available is a high pressure (38-40 psi)....he warned me that...because of the increased pressure TBI regulator in Throttle body will allow more fuel and engine will idle rough and use more fuel.

I'd have to ask the dealer what the snuck (I can't believe "double-u, Tee, Eff" is censored!) he's talking about! The FUEL PUMP has absolutely zero control over the fuel pressure. All the pump can do is move fuel. The pressure, comes from a resistance to flow, and that is caused by the Fuel Pressure Regulator located in the TBI assembly. The FPR is simply a valve w/a diaphram that has a spring behind it. The fuel pump pushes fuel to the TBI unit, past the injectors, and the "path ends" at that valve in the FPR. The pump is still pumping though and since there is no where for the fuel to go (resistance to flow) the pressure in the system rises. When the pressure reaches a point high enough to overcome the spring behind the diaphram, the valve opens, and fuel flows past it, and back to tank.

If your fuel pump is faulty, and you're replacing THAT, what does the FPR in the TBI unit have to do with anything? The fact is, you could put the fuel pump in your boat from a Top Fuel Dragster, and your stock FPR will govern your fuel pressure to the stock setting, by dumping excess back to tank when the pressure in the system (set by the FPR) is reached. In short, you virtually can't pump too much fuel and flood the engine if the FPR is functioning as designed.

You are absolutely correct. The fuel pressure regulator in the TB unit controls the fuel pressure to the injectors. I have been with Indmar for 10 years and we have not had any of the low pressure pumps during my time here. Our part number for thereplacement fuel pump is S556014. We have them in stock if you need one.

JDK
09-07-2007, 09:35 PM
Thanks for the pn E.N.
So can we (me and the rest of the guys reading this) assume that this pump swap (low to high pres.) can be made without requiring any other changes to the rest of the fuel system?
Thanks in advance.

JimN
09-07-2007, 09:40 PM
95mc- That dealer is wrong. 13-15psi is not what the OEM pump put out. Who is it?

Storm861triple
09-07-2007, 11:40 PM
Thanks for the pn E.N.
So can we (me and the rest of the guys reading this) assume that this pump swap (low to high pres.) can be made without requiring any other changes to the rest of the fuel system?
Thanks in advance.
That is correct.

Chicago190
09-11-2007, 05:54 PM
The only time it would matter is if the new fuel pump was flowing so much fuel that it overran the regulator. What that means is that the system isn't able to return enough fuel to the tank, usually because the FPR is too narrow somewhere in its design and can't flow the volume of fuel that the new pump is supplying. Doesn't sound like this is a problem that anyone has run into with the TBI engine so I wouldn't worry about it.

BTW, isn't 13-15 psi the pressure supplied for carbed engines, fuel injected is usually 35+ from my experience.

Storm861triple
09-11-2007, 06:28 PM
The only time it would matter is if the new fuel pump was flowing so much fuel that it overran the regulator. Doesn't sound like this is a problem that anyone has run into with the TBI engine so I wouldn't worry about it.
It isn't a problem, which is why I didn't confuse the issue earlier w/that not-happening "possibility". On one of my cars (TBI),I replaced the stock FP which "specs" at about 20-25 GPH, and was "meant for" 9-13 PSI with a pump that was rated at 70 GPH, and "meant for" systems up to 60 PSI or more. "Meant for" -again because the FP doesn't dictate the system pressure. Car ran fine, and I could easily regulate the pressure to my content (~15 PSI for my combination), using the factory FPR, modified to be adjustable.

BTW, isn't 13-15 psi the pressure supplied for carbed engines, fuel injected is usually 35+ from my experience.
No. Carbs generally like 5-7 PSI or so. 13-15 would blow past the needle and seat so bad the thing would hydrolock on gasoline. Technically, all a carb really needs is 1 PSI and enough FLOW, to sustain that low pressure, at WOT to meet the demand placed on the float bowl, during periods of highest consumption.

95mc
09-12-2007, 07:27 AM
New fuel pump worked fine....Dealer apparently did not know what they were talking about....scary...Thanks again !

ride
09-15-2007, 12:40 PM
Would you happen to have the pn. of this replacement you purchased from NAPA??? I've been looking for a spare for years, and nobody can seem to come up with it (to get this # on my pump, I've got to remove it)
Sorry for the no reply, been away from the net for a while. Sounds like Enginenut got you setup. Feel free to send a PM and I'll grab my p/n for you if you have any future issues. As JimN said, which dealer was it that started you down this road in the first place? Might be good info to share in case any other forum members run into the same issue/misinformation.