I can't believe my 2 year old mechanical fuel pump has **** the bed on my 442, but you have to crank the **** out of it to fill the carb and putting a vacuum pump on the feed line fills in no time. I can't remember where I got it before. Any sources? NAPA Delphi says w/AC only? Not an AC car.

 

Parts catalog dated Sept 66 shows part # 6416836 for 66&67 400cu , 4 barrel carb.
this cross to
Delphi MF0152
Airtex 40523.

 

The best pump for the 67 442 which has 2 lines is a Carter M4516. It's their muscle car series pump and is identical to the OEM pump.

 

I've also had good results with Carter mechanical pumps. The only potential issue is that some people have reported higher than desired output pressure (like 8-9 psi vs. 5.5-6.5 desired). This can cause problems with some carbs. E-brock carbs are particularly sensitive to excessive fuel pressure.

 

I bet your going to find the probably isn’t the pump. The problem is today’s fuels evaporate so much faster than they used to. Think about it, the float bowl in the carb is full when you shut off the engine. The only reason you would need to crank the engine is if the fuel leaked out, or the fuel evaporated.

Modern cars have closed fuel systems. They have electric fuel pumps. Carbureted cars are a very tiny percentage of vehicles on the road today. There is little incentive for the fuel refineries to formulate gas with ingredients to resist evaporation like what was needed 20 years ago.

Before condemning the pump, inspect the fuel lines closely. There may be tiny pinholes that might cause the pump to lose prime. Look for discoloration or stains on the frame or near the fuel line clamps. You may not see the leak, but you might see the evidence.

If this is a new concern, try a different brand of fuel. Maybe your local station changed their fuel formula? I suppose it’s possible the check valve in the pump could be leaking, draining the fuel line, but there should still be some fuel in the float bowl if the fuel didn’t evaporate or leak away.

 

I'll check that but if you crack the hard line from the pump to the carb and turn the engine over it takes forever for fuel to come out.

 

The pump could be be bypassing fuel to the tank. Even back in the day GM had restrictors for the return line to put more fuel to the supply side. Take a pair of vice grips and pinch the rubber return line off and see if that helps.

 

Unless the restrictor built into the bypass port on the pump somehow came loose and got pushed into the tank, that's unlikely. There are no moving parts in that bypass, just a plug in the bypass port with a tiny hole in it.
More likely is that the check valves in the pump inlet and outlet are bad or have been held open with debris that got sucked from the tank.

 

I had a problem years ago where the return line was taking fuel back to the tank and starving the feed line to the q-jet carburetor. I tried 66-3X2 442's idea and it solved the starving out problem so I replaced the fuel pump. I had another issue more recently where the fuel pump was delivering in excess of 9 lbs of pressure to the carb (original q-jet again) and the car would burn extremely rich at idle (lots of black smoke) but ran great on the freeway. Again, I replaced the fuel pump and it solved the problem as the new pump was delivering about 5 lbs to the carb. Most recently, I have ordered fuel pumps through Super Cars Unlimited near Portland, OR (www.supercarsunlimited.com to see their on-line catalog). SuperCars deals only with mechanical parts for Oldsmobile A-body cars and the owner (Greg Rollin, who answers the phone if you call) is very knowledgeable about nearly any aspect of mechanical operation for several model years of the 4-4-2.

Randy C.

 

Joe

Have you ever seen the GM restrictor that was put into the rubber line? I found some NOS units on eBay still in the GM wrapper and I may still have one.

 

Sorry, but the bypass wasn't the problem. Now, if the check valve was leaking internally, then shutting off the bypass likely increased flow to the carb just enough to mask the poor pump performance.

 

I have not. What was the application for those? In any case, it's easy to just look at the bypass port on the pump in question.