Engine starting problem - fuel delivery?

[Steve Smith]

Need help in diagnosing an engine starting problem. (There is sufficient fuel in both tanks) I bought my CAV GT40 in September and the car has been at the shop pretty much since then getting much of the electrical wiring replaced. That work appeared to be just about done when the engine starting problem began. My car has 2 Holley HP125 fuel pumps. The pumps come on, but there is no fuel pressure at the gauge. The engine turns fine, it just doesn't start. The previous owner had the carbs cleaned to get rid of debris caused by old fuel.

Would appreciate any thoughts. Thanks,
Steve

 

[Jim Cowden]

Dont know your layout.

Toss some fuel down the carbys and see if it fires that will also prove it is delivery
If you have a surge tank that the pumps are drawing from has that got fuel in it.
I would disconnect a fuel hose at the carbys and see if fuel comes out when pumps are activated.
Then just work back from there.
Depending on layout some surge tanks need filling to work, it may have syphoned off from sitting for to long

Jim

 

[Randy V]

Old fuel doesn't cause debris... Debris is from crap being introduced to the fuel tanks and/or decomposition of hoses, cell foam, etc...
Jim has you on the right path and I would add that you replace any fuel filters.

 

[Steve Smith]

Dont know your layout.

Toss some fuel down the carbys and see if it fires that will also prove it is delivery
If you have a surge tank that the pumps are drawing from has that got fuel in it.
I would disconnect a fuel hose at the carbys and see if fuel comes out when pumps are activated.
Then just work back from there.
Depending on layout some surge tanks need filling to work, it may have syphoned off from sitting for to long

Jim

Thanks Jim,

I have Weber IDA's and don't know about any surge tanks. Will try your suggestions. Appreciate quick response.

Steve

 

[Steve Smith]

Thanks Randy,
I guess a better description would be that the carbs were gummed up by old fuel, but will look into past debris problems.
Steve

 

[Steve Smith]

Hey guys,
Sorry for the confusion, just found out the Holleys can't pump up against the force of gravity. Why they were installed in the first place I don't know. I'll be replacing the Holleys with whatever pumps go with the Webers best, heard good things about Facets. Again, thanks for your help.

Steve

 

[Ian Anderson]

I would expect any pump to make enough pressure to fill Webber carbs

Could you have solenoid valves in the fuel lines that are not opening?

The solenoid valves would be a safety feature so when power is off no fuel can leak, but if not being electrically energised will remain closed and not allow fuel through

Ian

 

[Steve Smith]

Thanks Ian,
I will keep solenoid valves in mind if the new fuel pumps don't solve problem.
steve

 

[Randy V]

Hey guys,
Sorry for the confusion, just found out the Holleys can't pump up against the force of gravity. Why they were installed in the first place I don't know. I'll be replacing the Holleys with whatever pumps go with the Webers best, heard good things about Facets. Again, thanks for your help.

Steve

Steve, the Holley HP125 is a Gerotor pump and they will generally work fine as a lift pump. You may want to check that the inlets are not restricted in some way.

It is the Vane type pumps that have troubles lifting fuel and even at that, there are people here that have somehow managed to get by with them. The biggest problem is that sometimes pumps put in a lift configuration lose their prime and work hard trying to suck enough air volume to draw the fuel into the pump chamber..

Link to the gerotor pump I am talking about:
http://www.jegs.com/i/Holley/510/12...2&cadevice=t&gclid=CLP_3e6K0cICFaVDMgoddlUAOQ

 

[Jimmy P]

Steve, FWIW, I run Facet Red Top/Dot pumps and they work fine with my 44 IDF's. I've also heard Carter 4600 fuel pumps work well. I can't speak to personal knowledge of the Carters but I know of a guy who swears by them for his Webers.