kirkll
Cadet
- Joined
- Jun 9, 2020
- Messages
- 27
I’ve seen several posts on fuel pump issues, and I believe I’m having one myself.
1990 4.3 Mercruiser stock 2 barrel carb (carb 2 years old and runs perfectly)
I was originally having issues with the shift interrupter switch that was not functioning properly and sticking, but after tinkering with it I got that working again. So I’m quite sure this is a fuel flow issue I’m dealing with now.
The motor use to fire up easily in neutral with very little cranking, but now I need to give it more throttle to get enough fuel to start it… once running in neutral it seems to run fine at higher rpms with no load on it. But after I put it in gear it does fine until I hit 2700 rpms, then is stalls out from lack of fuel. But it purrs like a kitten at 25-2600 rpms in gear.
I checked the filter going into the carb, and the water fuel separator canister too even though I had just changed that canister recently. When I reinstalled the canister, I filled it with fuel first, and that time it ran up to 4000 rpms and ran perfectly for about 7 -8 seconds before staring out.
That right there tells me that I have a fuel restriction issue…. I would like to check the pressure on my fuel pump, but do not know the pressure spec requirements for a 4.3 two barrel. Can someone help me with that?
This existing fuel pump is an aftermarket marine grade pump, and is mounted right in front of the water fuel separator , and ther is no pressure regulator prior to going into the carb. it’s wired correctly through an oil pressure switch, and I’ve dounble checked all the wiring and replaced the wire connection ends to that switch, so I don’t think it’s electric related.
Besides changing out my fuel hoses and checking the fuel pressure and volume, I’m at a loss for what’s going on. Any other trouble shooting suggestions would be helpful. Kirk
1990 4.3 Mercruiser stock 2 barrel carb (carb 2 years old and runs perfectly)
I was originally having issues with the shift interrupter switch that was not functioning properly and sticking, but after tinkering with it I got that working again. So I’m quite sure this is a fuel flow issue I’m dealing with now.
The motor use to fire up easily in neutral with very little cranking, but now I need to give it more throttle to get enough fuel to start it… once running in neutral it seems to run fine at higher rpms with no load on it. But after I put it in gear it does fine until I hit 2700 rpms, then is stalls out from lack of fuel. But it purrs like a kitten at 25-2600 rpms in gear.
I checked the filter going into the carb, and the water fuel separator canister too even though I had just changed that canister recently. When I reinstalled the canister, I filled it with fuel first, and that time it ran up to 4000 rpms and ran perfectly for about 7 -8 seconds before staring out.
That right there tells me that I have a fuel restriction issue…. I would like to check the pressure on my fuel pump, but do not know the pressure spec requirements for a 4.3 two barrel. Can someone help me with that?
This existing fuel pump is an aftermarket marine grade pump, and is mounted right in front of the water fuel separator , and ther is no pressure regulator prior to going into the carb. it’s wired correctly through an oil pressure switch, and I’ve dounble checked all the wiring and replaced the wire connection ends to that switch, so I don’t think it’s electric related.
Besides changing out my fuel hoses and checking the fuel pressure and volume, I’m at a loss for what’s going on. Any other trouble shooting suggestions would be helpful. Kirk
