I've got a Carter fuel pump on my newly finished Pontiac powered 27T Modified. Nothing special, just a basic low pressure one for carbs. My problem is that it never stops pumping - even the carb bowls are full. I read that this is a feature of some Carter pumps. Is this true? Think I will be investing in an SU pump
First...which pump ? Carter has many..! We (the readers) have no crystal ball. Second, NO...the "pump" does NOT turn off when the bowl'(s) are full. This can never happen, the pump will pump as long as the engine is running (mechanical), or the electrical switch is not turned off (electrical pump). Beside, the pump has no clue when the carburetor is full..! The carburetors needle and seat close off the fuel flow when full, or open when the bowl(s) need fuel. UNLESS...your pump is pushing too much pressure. That's the owner/builders problem..! YOU must figure out how much pressure the carburetor needs and have the regulator set to that value, or just under. Do you have a regulator plumbed into the system ? Sounds like you should. Mike
There are basically two types of electric pumps: the pulse type, and the motor type. The motor type runs continuously, and has a pressure regulator (either in the pump or downstream from it) that limits pressure. The pulse type has a regulator built into the operation of the pump--once it builds enough pressure, it won't pulse until the pressure drops again. you have a motor type pump, so it runs continuously.
Thanks. I've never used an American fuel pump before so wasn't sure. I think I will swap it out for an SU that just cuts in when the pressure drops. The Carter is noisy despite being rubber mounted.
Yes, the Carter pump is noisy. The motor type pumps can move more fuel than the pulse type, so they're more popular in cars that have bigger engines, etc.
You probably did not run a relay with the Carter so that when the ignition is off so is the pump,electric pumps should always be run with a relay. Not that expensive to do it right. https://www.ebay.com/itm/113942182291?epid=1029667192&hash=item1a877bb993:g:LukAAOSwbhVgzey9
It doesn't run when the ignition is off and it is separately switched anyway. Just runs all the time when the ignition is on and the fuel pump circuit is switched on but I now think that it's meant to and a relay doesn't stop that happening. It also runs through an inertia switch so it switches off in the event of an impact.
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