carb not picking up fuel

[huntingtheworld]

mercruiser 1987 5.0 alpha one

ok so I took my carb apart to see why it only runs when you pump the gas,I looked and all the seals were good and i blew out all the jets and ect 2 times no difference.I noticed when i pump the gas and crank it,it runs for a sec and i do not see any fuel coming out of the 2 main jets near the top of the carb.any ideas? its a 2 barrel mercarb.

 

[alldodge]

Re: carb not pucking up fuel

Re: carb not pucking up fuel

If your getting fuel to the carb and it sounds like you are, then either the idle adjustment screw is turned all the way in closing off the idle circuit, the idle circuit is clogged or the float level is not set correctly.

 

[thumpar]

Re: carb not picking up fuel

You are getting fuel to the carb. When you pump the throttle the accelerator pump squirts some fuel in. Sounds like it is out of adjustment or need a good cleaning and rebuild.

 

[chimmike]

Re: carb not picking up fuel

Have you checked the fuel pump too?

 

[huntingtheworld]

Re: carb not picking up fuel

You are getting fuel to the carb. When you pump the throttle the accelerator pump squirts some fuel in. Sounds like it is out of adjustment or need a good cleaning and rebuild.

ok just found this out,Its not getting much gas.I took the fuel water separator off it was half full.I filled it back up and removed one side of the fuel line on the pump and cranked it and it spew for a second then quit.I checked the separator again and half full again.Could it have a filter in the tank stopped up?

 

[thumpar]

Re: carb not picking up fuel

Do you have an electric fuel pump? I don't think there is normally a filter in the tank.

 

[chimmike]

Re: carb not picking up fuel

I have a '91 MCM 5.0 and the only filter is in the brass fitting on the carb itself that the hard line plumbs into.

Get some b12 and disconnect the hard fuel lines, spray them all out with b12, and spray inside the fuel pump with it too. spray inside the carb bowl, etc. It'll loosen any gum/gunk in there.

 

[natureschild88]

Re: carb not picking up fuel

I've been going with the same problem with my motor for the past week. I've finally diagnosed the problem and it was the fuel pump, not the carb or the filter. Read my thread "1991 4.3 V6 Mercruiser need help" hope it helps you in some way.

 

[huntingtheworld]

Re: carb not picking up fuel

I've been going with the same problem with my motor for the past week. I've finally diagnosed the problem and it was the fuel pump, not the carb or the filter. Read my thread "1991 4.3 V6 Mercruiser need help" hope it helps you in some way.[/

no electric pump.
I pulled the fuel line from the tank that goes to the separator and sucked and fuel came out.So im guessing is the pump weak?
and ok ill check your thread out.

 

[alldodge]

Re: carb not picking up fuel

If you can suck fuel out of the tank its not clogged. If you connect your fuel pump to it it should be able to suck fuel out of the tank, if it cannot replace the pump.

 

[thumpar]

Re: carb not picking up fuel

You could try an external tank to rule out anything to do with the tank.

 

[huntingtheworld]

Re: carb not picking up fuel

You could try an external tank to rule out anything to do with the tank.

I had a stroke when i seen the price of the stock pumps,Will a 4-7 psi electric fuel pump work?

 

[thumpar]

Re: carb not picking up fuel

If you go to electric you will need to do some wiring. The pump should only run with cranking or the engine is running so you will need an oil pressure switch. You will need to block off the location of the current pump.

 

[alldodge]

Re: carb not picking up fuel

I had a stroke when i seen the price of the stock pumps,Will a 4-7 psi electric fuel pump work?

Yes you can go electric as thumpar stated, but a mechanical can be picked up at many auto parts stores just make sure its a marine type and not for a car. Airtex makes the ones for Mercruiser

 

[huntingtheworld]

Re: carb not picking up fuel

Yes you can go electric as thumpar stated, but a mechanical can be picked up at many auto parts stores just make sure its a marine type and not for a car. Airtex makes the ones for Mercruiser

Ive been thinking about going electric.I watched the fuel flow with the pump it starts off steady then goes to a steady stop.no clogs and plenty of fuel.And right before all this happend it would not run wot.so im guessing ethonoal did its trick. why would a regular automobile mechanical pump not work?

 

[thumpar]

Re: carb not picking up fuel

Marine pumps are made to dump fuel in the oil side of the engine block or carb on failure instead of outside. This is a safety thing. You don't want fuel or vapors in a boat.

 

[alldodge]

Re: carb not picking up fuel

Ive been thinking about going electric.I watched the fuel flow with the pump it starts off steady then goes to a steady stop.no clogs and plenty of fuel.And right before all this happend it would not run wot.so im guessing ethonoal did its trick. why would a regular automobile mechanical pump not work?

I don't see ethonal being the only item which caused the failure. Are you sure its the fuel pump and did you try the external fuel tank? You could have a clogged pickup tube or a bad antisiphon valve which will not let fuel pass. I know you said you sucked on the line and could get fuel but it needs to be more then just a small amount to justify a new pump.

 

[huntingtheworld]

Re: carb not picking up fuel

I don't see ethonal being the only item which caused the failure. Are you sure its the fuel pump and did you try the external fuel tank? You could have a clogged pickup tube or a bad antisiphon valve which will not let fuel pass. I know you said you sucked on the line and could get fuel but it needs to be more then just a small amount to justify a new pump.

I have not tried another tank i do not have one to try.I dont think it has a antisiphon valve? It only has a hose that goes to the tank witch goes to a fitting with a tube on the end.(which picks up the gas) And the hose goes to the separator and it can travel freely to the separator.

 

[thumpar]

Re: carb not picking up fuel

It should have an antisiphon valve.

 

[huntingtheworld]

Re: carb not picking up fuel

where would it be?