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MGB Elec fuel pump

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Bob Claffie

Bob Claffie

Jedi Knight
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I'm going to pick up my newly purchased 74.5 B this week. I've been told the fuel pump is slightly unreliable.
The pump has been relocated to the trunk, how difficult would it be to change the points in situ ?

Would a replacement pump putting out 3 to 6 PSI be too strong for the floats in the HIF carbs ?

I have used Facet pumps in the past, is there any particular Cat # best for the MG ?

Likewise what Cat # from Airtex would be compatible to the MG ?

Not fussy about originality, only functionality.

Thanks, Bob
 
Bob - You don't want any more than 4 PSI output pressure on any pump you use. If you are interested in having your existing pump restored and converted to solid state, see the article, see the article, SU Fuel Pump Services in the SU Fuel Pump Articles section of my homepage, linked in the signature block below.
Cheers,
 
Anything over 3 PSI is too much for SU carbs. In fact, I'd keep it down around 2 PSI.

I had a Facet on my bugeye. There is a version that is rated around 3 PSI, and that should be OK. On my Porsche, I have a 6-8 PSI Facet and a Holley pressure regulator that reduces it to 2 PSI. I have a pressure gauge on the unused port of the regulator. I do this so that the higher pressure ahead of the regulator might reduce problems with vapor lock, at least a little. I think that this arrangement is pretty good--it doesn't affect the flow rate much and keeps the pressure right where you want it.

https://www.nonlintec.com/porsche/fuel/
 
"Anything over 3 PSI is too much for SU carbs."
I have to disagree with you Steve, the T series cars, with the pump in the engine compartment, uses a SU fuel pump rated at 1.5 psi, but the MGAs and MGBs with the pump located under the car, close to the fuel tank use SU pumps that are rated at 3.8 psi and 2.7 psi respectively. Interestingly, I ran a pump from a MGA (3.8 psi) on our TD for a summer just to see if it would cause any problems. The car never missed a beat the entire summer, before I put the original 1.5 psi pump back in place.
Cheers,
 
Interesting scoop on those pressure limits.

Years ago I did a half-ass restoration on a 100/6 and needed a fuel pump on short notice.
I had a generic Facet laying around from a previous job and used it. Blew fuel right past the floats on the HS4's.
As mentioned above I had to put a regulator in the circuit. Never did find out how hard it pumped.
At the time I thought all Facets were the same ! Learned something new.

Thanks, Bob
 
There is actually a similar discussion going on about this on the Spridget section of BCF right now. Might give you some ideas,

~Check Here~ to see it.
 
David_DuBois said:
"Anything over 3 PSI is too much for SU carbs."
I have to disagree with you Steve, the T series cars, with the pump in the engine compartment, uses a SU fuel pump rated at 1.5 psi, but the MGAs and MGBs with the pump located under the car, close to the fuel tank use SU pumps that are rated at 3.8 psi and 2.7 psi respectively. Interestingly, I ran a pump from a MGA (3.8 psi) on our TD for a summer just to see if it would cause any problems. The car never missed a beat the entire summer, before I put the original 1.5 psi pump back in place.
Cheers,
Click to expand...

Well, I'm basing that on my experience with my Bugeye Sprite, which ran at 3.5 PSI for a while and I had continual problems with it blowing fuel past the float valves. The valves were in good condition and worked OK at lower pressures. I had a Facet pump and added a Holley regulator, which kept it around 2 PSI and everything was fine after that.

It's important to recognize that the original specs often don't apply to modern parts, which may or may not (more likely may not) work as well as originals. Probably depends a lot on who made them and where they came from. In any case, you don't really need even 2 PSI, at the carbs, so why take the risk with higher pressure?

Now that you mention it, I've never checked the outlet pressure of the SU in my TD, which is working fine. Might be interesting to see what it is.
 
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