Edelbrock Fuel Pump Question / Hot Start Issues

[1972BlueC20]

I'm considering installing a edelbrock mechanical fuel pump so I get the correct PSI to my edelbrock carb. I've been having trouble with hard starts after the truck is hot and I think I'm running about 7.5 - 8 PSI with the stock mechanical fuel pump. This issue could also be starter related, or I might need a phenolic spacer.

Hopefully between these 3 things I can fix the hard start when hot issue.

My question regarding the fuel pump is this :

The stock fuel pump has 2 inlets and 1 outlet to the carb. I have a 72 C20 with 350 engine....no EEC, so I have 2 lines running from the fuel tank....1 main line and 1 return fuel line.

The edelbrock fuel pump has only 1 inlet and 1 outlet. If I installed this pump, what happens to my return fuel line? Does it just get capped off at the sending unit? Or?


Also if anyone has any other comments or suggestions regarding the hard start issues let me know.....Which should I try first? Carb spacer? Fuel pump or fuel regulator? Or new starter?

The starter sometimes hesitates and skips a beat so to speak...but for the most part it seems to be working good, just takes about 5-10 seconds of continuous trying to turn over when the truck is hot and has been driven for while.


Thanks in advance guys!!

[mdeal]

This is one of the most common problems now a days in our Speed Shop. If I had to bet money, I'd say you've been running pump gas with ethanol. Am I right?
The "10%" Ethanol in pump gas is the culprit for many of today's problems with older carb engines. See; ethanol has a very low boiling point. So in the summer months when the temps are up the ethanol in the fuel will boil when it gets hot. This is probably the reason you can't get it to startup when warm.
We've tried selling customers heat shield after heat shield, either on the fuel line or between the carb and intake. None of these help the problem much. The best fix for this problem is to find a gas station in your area that sells NON-ETHANOL gas. Buy this! If you can't find one, then you can mix race gas with the pump-ethanol gas. Normally 5gallons race gas to 10 gallons pump-ethanol works okay. (Race gas no more than 110 octane)

If you aren't running the pump gas with ethanol, then I would start with the fuel pump. Either a good 110gph Holley or Edelbrock mechanical pump will work fine. As far as your return line goes, just cap it at the sender. Neither of these pumps will need a return as they put out pressures that any 4bbl carb can handle. If you want to make sure the pressure is correct at any time, then add a good pressure gauge and regulator. The regulator will keep the pressure constant. (better on the needle & seats in carb).

I hope this helps a bit! Have fun hot rodding!

[Joe Pass]

Edelbrock carbs want 4.5 to 5.5 psi max...anything over will bypass the needle and seat and cause a rich mixture, especially at idle. My same experience on my 56 running 2x4 Edelbrocks when hot and parked the extra static fuel (8psi) pressure was passing through the needle and seat until the pressure lowered causing extra fuel to flood into the cylinders. Hot starts were miserable, I had to crank until the fuel cleared and it would start. In my case I installed a fuel reg and turned the pressure down to 5psi and also used carb insulators that help.
Your other Question, you talk about the stock pump having 2 inlets and one outlet...Could it be the second inlet is a vapor return (emissions) line ? and not actually a fuel line but a vapor return line to the tank or carbon canister. After market pumps like Edelbrock don't provide that because they are a performance pump and not emissions friendly or compatible.
If your engine cranks well then the starter sounds fine unless it also gets heat soaked and draws more amps (A common GM starter problem) then consider a high torque starter but troubleshoot and check all you starter cables for corrosion and wear first.

[Joe Pass]

Edelbrock carbs want 4.5 to 5.5 psi max...anything over will bypass the needle and seat and cause a rich mixture, especially at idle. My same experience on my 56 running 2x4 Edelbrocks when hot and parked the extra static fuel pressure (8psi) was passing through the needle and seat until the pressure lowered causing extra fuel to flood into the cylinders. Hot starts were miserable, I had to crank until the fuel cleared and then it would start. In my case I installed a fuel reg and turned the pressure down to 5psi and also used carb insulators that helped a lot

Your other Question, you talk about the stock pump having 2 inlets and one outlet...Could it be the second inlet is a vapor return (emissions) line ? and not actually a fuel line but a vapor return line to the tank or carbon canister. After market pumps like Edelbrock don't provide that because they are a performance pump and not emissions friendly or compatible.
If your engine cranks, then the starter sounds fine unless it also gets heat soaked and draws more amps (A common GM starter problem) then consider a high torque starter but troubleshoot and check all you starter cables for corrosion and wear first.

[Joe Pass]

Sorry for the duplicate post, my computer locked up while posting a reply...Oh well
Like mdeal says you will have to block the second line if you want to use an after market pump, but a stock pump will give you a lower PSI and you can avoid adding a regulator.
Good luck

[1972BlueC20]

Thanks guys!

Yes I'm running 10% ethanol fuel. I don't know anywhere in my area that I can get non ethanol fuel. Is there a website to help find non ethanol gas?

Also, I already have an edelbrock fuel pressure regulator that I haven't installed. Can I just install this and set it to around 5 PSI? Will it cause any issues of bottle necking since the pump will still be putting out a higher pressure?

Can anyone reccomend a good pressure gauge that I can leave inline?

Do you think a phenolic spacer will help as well in addition?

[mdeal]

Use www.pure-gas.org to find the nearest non-ethanol gas stations near you.
You could use the regulator now with no problems. As far as a gauge goes, just about any 0-15psi 1-1/2" gauge with 1/8npt thread will work. I sell the AutoMeter ones as well as AED's. Edelbrock has em too. You should be able to find one at local parts store in Mr.Gasket brand too.

Good Luck!

[mdeal]

Oh yeah about the spacer....I would stick to aluminum. The phenolic spacers have a tendency to melt on street vehicles.
They were designed for drag race use where hear buildup wouldn't be a problem.

[mdeal]

Wow...spell check. *Heat buildup. Not hear! Good greif.

[1972BlueC20]

If I decided to just do the edelbrock fuel pump instead of the regulator is there any trick to swapping out the pump? I've never changed a mechanical pump before....Is it as easy as just unbolting the old one and then installing the new one, or are there any tricks or things to watch out for??


Here are the items I'm thinking of buying, does this look ok?

http://www.summitracing.com/parts/aei-15632

http://www.summitracing.com/parts/edl-1721

http://www.summitracing.com/parts/mrg-6009

http://www.summitracing.com/parts/fel-6579

http://www.summitracing.com/parts/sum-g1710

[wreckedchevy]

I had been fighting this issue as well. you could actually see the fuel boiling in the fuel filter. I ended up insulating my fuel line from the pump up to the carb and my problem went away.

[young grasshoppa]

Edelbrock provides pretty thorough instructions on how to install their fuel pump. It requires you to open the fuel pump to cock it. I am sure you can find the instructions online so you have an idea of what it requires. Just take your time and it is not difficult.

[1972BlueC20]

what did you insulate it with?

I guess I could try that too first, but I think I'm still getting too much PSI going into that edelbrock.....anyone know what the stock PSI would be on a stock 1972 C20 mechanical fuel pump?

[wreckedchevy]

I've also been told if you are going to run an edelbrock carb you should use the intake gasket's that block off the exhaust ports going into the intake.

[wreckedchevy]

one sec i'll go take a pic

[1972BlueC20]

Seems kinda crappy to go to all this trouble working around getting this edelbrock to run correctly.....maybe I should just get my Quadrajet rebuilt and put it back on.....or is there another carb that will run properly with the stock fuel PSI ?

[wreckedchevy]

it was some stuff like this http://www.summitracing.com/parts/sum-350115/overview/
I bought it at a local speed shop for $15 that finished off my hot start issues I've been having and it's been in upper 90's here for weeks runs like a dream using 10% ethanol.


carb spacer's I got at the same speed shop don't remember how much they were I put them on last year and had very little success with the hot start problem.

[wreckedchevy]

Originally Posted by 1972BlueC20

Seems kinda crappy to go to all this trouble working around getting this edelbrock to run correctly.....maybe I should just get my Quadrajet rebuilt and put it back on.....or is there another carb that will run properly with the stock fuel PSI ?

I'm really happy with my edelbrock I just got the proper jetting put in a few weeks ago as well and man it runs nice and no more gassy smell. I just put the same carb on my daughter's 72 and had to replace the intake so I put the gasket's in that block off the exhaust so hopefully I won't have any of the hot start problems with her's but if I do I'm going to start with insulating that fuel line.

[wreckedchevy]

I'm starting to regret posting that pic, dang my intake needs cleaned! bought it used 20 years ago