Cascade Crew

redlava · Posted: Tue Jun 30, 2009 12:23 pm Post subject: fuel pump questions

I was going to get a new fuel pump cause the factory replacement falls on its face around 4500rpm. I have read about the carter 6626 and it has had some mixed reviews. I was going to get a holley or some other mechanical aftermarket pump, but none of them have a return line. What would you guys do? Can I just plug the return line, but then would I get vapor lock issues?

blue89 · Posted: Tue Jun 30, 2009 12:31 pm Post subject:

I run a stock mpfi pump with a Barry Grant regulator. Keeps up with the 650dp on my 454 just fine.

redlava · Posted: Tue Jun 30, 2009 12:50 pm Post subject:

Only problem with that is I dont want to drop the tank to intall a electric pump. The car is already equipid with a mechanical pump.

blue89 · Posted: Tue Jun 30, 2009 1:44 pm Post subject:

Failed to notice that part....

Twilightoptics · Posted: Tue Jun 30, 2009 2:41 pm Post subject:

Got it all running through a 3/8 fuel line?

How have you assessed that the pump isn't keeping up?

redlava · Posted: Tue Jun 30, 2009 3:14 pm Post subject:

Its all either going though the stock hard line or rubber line, which I believe is 3/8. I'll have to check when I get home. I have no reason to believe that it is the fuel pump other than when it was floored how much slower it was accelerating after 4500rpm to 5500rpm. I basing this acceration on me watching the tachometer. Why what other ideas did you have paul?

redlava · Posted: Tue Jun 30, 2009 7:17 pm Post subject:

I think I found my problem, it 's looking like the metal line got slightly kinked when bending it by hand so it would not vibrate against the water pump and alternator. I am gonna order some ss flex fuel line and some fittings. I would still like to get a larger pump just to be sure and eliminate all possibilities. I am probably going to end up with the carter 6626. Unless anyone else has some more ideas?

chevymad · Posted: Tue Jun 30, 2009 9:58 pm Post subject:

The return line just T's inside the mechanical pump with the inlet line. You can do the same by installing the T outside of the pump.

redlava · Posted: Wed Jul 01, 2009 6:38 am Post subject:

well that was a lot easier than I thought thanks a bunch

redlava · Posted: Wed Jul 01, 2009 7:02 am Post subject:

Would you guys use a compression fitting or flare the hard lines that are on the sub -frame? What are the advantages of each?

Twilightoptics · Posted: Wed Jul 01, 2009 10:27 am Post subject:

I used Earls adapters to -6AN braided hose.

redlava · Posted: Wed Jul 01, 2009 12:00 pm Post subject:

Paul did you use this?

http://www.summitracing.com/parts/EAR-165056ERL/

Also just thought of this. If I put a T line for the return in the inlet line like brandon was recomending what is going to stop the pump from sucking fuel from both lines the supply and the return. Could someone please explain how the pump will send the extra fuel down the return if its in front of the pump. Sorry for all the questions just wanna make sure I get it right.

chevymad · Posted: Wed Jul 01, 2009 5:10 pm Post subject:

The pump really doesnt send extra fuel down the return, and it does suck out of both lines if it really needs to, unless you have the intank pump as well like mine does. With the low pressure in tank pump fuel flows up the 3/8s line to the supply side of the mechanical and then is returned via the 5/16 line back to the tank. Causing a slight pressure raise at the mechanical pump inlet. I thought I was screwed when I changed to a 120gph carter mechanical because it didnt have a return. Then I got to examining my old mechanical pump and the return and inlet were connected to the same chamber inside the pump.

How it works on a car without the intank pump I have no idea. If you do not have the in tank pump, then you really don't need the return at all. If you think about vapor locking, the mechanical pump would have to pump some fuel up to return it. Probably why in 86 and 7 gm went to the double pump setup, and retrofit any earlier cars where there were customer complaints.

Oh and on the fittings, whatever you do, don't use the ones with the rubber compression ring. Caused me many a nightmare.

redlava · Posted: Wed Jul 01, 2009 8:09 pm Post subject:

Can you hear the stock electric pump if it was back there when the engine is running? I have never dropped the tank and don't really have the means/area to do that at the moment. Is there any other way to check? If it was there, where would the wires to supply it with power normally run?

chevymad · Posted: Wed Jul 01, 2009 8:16 pm Post subject:

I'm not even sure mine works any more. Getting close to 300k miles, and have never heard of an electric pump lasting that long. Motor keeps running so never really investigated deeper.

redlava · Posted: Thu Jul 02, 2009 7:07 am Post subject:

To see if there is a electric pump I could pull off the inlet line to the mechanical pump and have someone turn the engine over to see if any fuel comes out?

blue89 · Posted: Thu Jul 02, 2009 7:47 am Post subject:

That would work. Just going to key-on should kick the pump on for a burst. Just aim the hose into a jug. Would an early car like that have the standard fuel pump fuse by the batter?

redlava · Posted: Thu Jul 02, 2009 8:14 am Post subject:

Where is the batter? Are you refering to the normal fuse box?

Twilightoptics · Posted: Thu Jul 02, 2009 8:29 am Post subject:

Or you could just look up by your tank and see how many electrical wires are coming out.

No pump should be just 1-2 wires. Not 3-4.

: O)

blue89 · Posted: Thu Jul 02, 2009 8:33 am Post subject: