Carter electric fuel pump low pressure?

[daytonaone]

I just purchesed and installed a carter electronic fuel pump after reading many positive reviews of the pump on the Samba.

I installed it under the gas tank and replaced my fuel 1/4 " fuel line with 5/16 to match the pump input and output .

I installed a jegs fuel pressure gauge at the carb. It started right up and initially read 2.5 psi.

I thought that was a little low but it was the same pressure as my mechanical so it shouild be fine.

The next day i started it up and it only read about 1.5 psi , i drove it around and checked it again and it was up to 2.5 psi.

My buggy ran a little rough and seemed lean, but it was only 50 degress out today.

The gauge seams to read between 1.5 and 2.5 psi , 1.5 is to low.

Any ideas about what could be the problem?

I will drive it again tomorow it is suposed to be 60 out and see if its still rough.

I have a single weber 40 DCNF carb on a 2007 cc engine with w100 cam and 1.25 ratio rockers. It normally runs perfect.


Thanks for your help!

[Dale M.]

Is gauge on output of regulator?..... If it is you may have lousy regulator, or bad gauge, the Carter rotaty pump (GP60504) are rated at 3-4 PSI at full demand, you should NOT need regulator with these pumps....

Dale
_________________
“Fear The Government That Wants To Take Your Guns" - Thomas Jefferson.

"Kellison Sand Piper Roadster" For Street & Show.
"Joe Pody Sandrover" Buggy with 2180 for Autocross (Sold)
============================================================
All suggestions and advice are purely my own opinion. You are free to ignore them if you wish ...

[oldschool5er]

I did this same setup last week using the Carter and a Jegs psi gauge. I used it on Dual Weber 44idf's using a regulator set at 3 psi. I started noticing the psi would drop to zero after about 10 min of idling although the engine acted normal. I called Carter to ask about it and they said the pump has an internal bypass in it so if you are not running a fuel tank return line it will start bypassing until demand picks up and you will see psi climb back up when the pump stops bypassing. I found I did not have to run a tank return line on this setup as the pump bypassing did not affect the engine demand. Carter said it would not cause harm to the pump by not running a return line. First time I used a Carter so we shall see. P4070.
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[modok]

Most of these complaints end up being cheap gauges, usually liquid filled.

If you want to test the fuel pressure, use a professional quality vac/fuel pressure testing gauge.

[daytonaone]

[daytonaone]

[74 Thing]

Those pressure gauges in the engine compartment are usually very inaccurate and really what good are they for monitoring purposes. Remove it and tee in your vac/pressure gauge for testing and if all is ok remove and move on.

[daytonaone]

[[email protected]]

the other thing which will cause low output pressures are inlet restrictions. Typically the fuel tank vent, or the fuel tank filter. I personally remove the filter on every car I have, and regularly change the in line filter.

I have seen tank outlets (even with no filter) clogged 100% with rust. Blowing it back to clear it is a ghetto fix, and will leave you fixing the problem properly soon. Best to flush the tank.
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[daytonaone]

[daytonaone]

So I pulled my Carter electronic fuel pump today it's on its way back to JEGS and they're sending me a new one. But I couldn't resist hooking up my old mechanical fuel pump.

So I hooked up the mechanical fuel pump left the pressure gauge inline and put my glass filter back in line and the car ran perfect just like before I switch the pumps.

The issue I was having which is why I went to electronic up in the first place is that the mechanical pump was having trouble keeping up with demand at 70 mph .

So for example started the car up glass filter filled up with gas pressure was 2 1/2 PSI. Took about a 20-minute Drive jumped on the expressway going about 70 miles an hour no issues but then when I pulled off and parked it at my house. I noticed the glass was almost empty and the pressure was reading 0.

So neither pump is keeping up with the fuel demand , but the electric was worse than my mechanical.

I'm hoping that the new electric pump will work properly and I just got a bad one.


I have a vented 69 Dodge Charger gas cap on my dune buggy I am taking John's advice and I did drill out the vent size a little bit not sure if that will make a differance. I can't check the original vent because it's under the hood which is permanently attached.

Thanks everyone for your advice and help I'll keep you posted when I get to new pump

[[email protected]]

the stock pump is good for 160hp, so you have something else going on (a fuel restriction) you haven't discovered yet.

it's also pointed to when you said the new pump was loud. They are only loud if they are restricted on the inlet side.

Though I will say there are 2 different rotarys, they have the same PN but the country of mfg is different.
_________________
It's just advice, do whatever you want with it!

Please do NOT send me Private Messages through the Samba PM System (I will not see them). Send me an e-mail to john at aircooled dot net

"Like" our Facebook page at
http://www.facebook.com/vwpartsaircoolednet
and get a 5% off code for use on one order for VW Parts ON OUR PARTS STORE WEBSITE, vwparts.aircooled.net

[daytonaone]

[Dale M.]

Tank does not need to big a vent, it just has to be big enough to break any seal that will cause a vacuum... The rate of fuel use per hour is a lot less than you think, if pump can do 30 gallons per hour, think of how far you drive in one hour at 70MPH bet you are getting better than 2.3 miles per gallon.... If you get 15 miles per gallon that means you are only using about 4.6 gallons per hour... If you get 20 miles per gallon your fuel usage is only 3.5 gallon per hour at 70MPH...As a guess your pump is running at about 15% of its rated capacity (do not totally rely on accuracy of my numbers though because I slept through math class in hi skool)... Your actual consumption rate is a lot less than pump capacity....

Early VW only has vented cap, later ones with all the smog crap has non vented cap....If you have vented cap on your tank there should not be a problem....

Dale
_________________
“Fear The Government That Wants To Take Your Guns" - Thomas Jefferson.

"Kellison Sand Piper Roadster" For Street & Show.
"Joe Pody Sandrover" Buggy with 2180 for Autocross (Sold)
============================================================
All suggestions and advice are purely my own opinion. You are free to ignore them if you wish ...

[daytonaone]

[Dale M.]

Have you got stock screen in tank?.... Has it ever been changed.... Have you tried air pressure to blow out line from pump to carbs.... Is you fuel filter installed correctly...

Dale
_________________
“Fear The Government That Wants To Take Your Guns" - Thomas Jefferson.

"Kellison Sand Piper Roadster" For Street & Show.
"Joe Pody Sandrover" Buggy with 2180 for Autocross (Sold)
============================================================
All suggestions and advice are purely my own opinion. You are free to ignore them if you wish ...

[74 Thing]

I think it is the vent-what year and make is your car?

[Slow 1200]

sounds like your vent, drive without the gas cap on to rule it out

[daytonaone]

[daytonaone]