fuel pump seems to be loosing prime-gctid814051

[rivahlife]

Have a 1990 3.0 mercruiser apha 1 drive. I can pump and pump and pump the throttle but always whined up having to crank the boat at full throttle. If it runs for a bit I cam turn it off and recrank easily most of the time but if it sits a few min of more, I have to go through the whole scenario again. Was told to that sounds like a vacuum leak but for the life of me I don't see any vacuum lines. Surely they are there though. Does the mechanical pump have a check valve that could had gone bad or do I need to keep looking a vacuum lines?

[desuch]

everyone that I know that has a conventional engine with a carburetor has that problem myself included, fuel injected engines don't have that problem , so my mentioned of start up pump to full throttle

3 times return to 1/4 throttle if it doesnt fire pump a few more times return to 1/4 throttle ,since i am from the days of no fuel injection not a problem i just except that was the way if was when i was going to high school, some people i have heard installed electric fuel pumps turn the key on for a minute all primed

[builderdude]

"rivahlife" post=814051 wrote:
Have a 1990 3.0 mercruiser apha 1 drive. I can pump and pump and pump the throttle but always whined up having to crank the boat at full throttle. If it runs for a bit I cam turn it off and recrank easily most of the time but if it sits a few min of more, I have to go through the whole scenario again. Was told to that sounds like a vacuum leak but for the life of me I don't see any vacuum lines. Surely they are there though. Does the mechanical pump have a check valve that could had gone bad or do I need to keep looking a vacuum lines?

Your either flooded having to hold it at full throttle or your float bowl is not holding its fuel. With the engine off look down the throat of the carb while someone quickly advances the throttle forward, you should see fuel being sprayed down the throttle bores. If there's no fuel spray your float bowl is empty or your accelerator pump is not operating correctly. If you do see fuel spray then give it 1-2 full throttle pumps and back to 1/4 throttle and try to start. It should at least start and run for 1-3 seconds or so. If it acts like it wants to start and you end up having to advance the throttle fully to get it to start it's likely been flooded and next time try only 1 pump. A recently run engine should start with 1 or less pumps of the throttle.

[rivahlife]

Thanks. I'll try that.

[Guest]

Where the fuel line connects to the carb, there is/should be a filter screen inside the female end. Check that as well

[Fiftybucks]

Change the fuel filter. those can clog with one bad tank of gas.. Also clean the inline filter at the carb.. If the inline filter is clogged...you might have rust debris in the bowl. All above quick easy cheap prior to more drastic measures.

[Chief_Alen]

Start at the tank, pull the fuel pickup tube, inspect / clean the anti-syphon valve, check the bottom of the tube for a screen, then follow the line cleaning every turn etc to the filter, the channels in the filter, all the way to the carb.

You can then suck the gunk and junk off the bottom of your tank into a glass jar / bottle.

See that yellow hose hooked to the carb, it have fuel in it ?