1968 MerCruiser 120 starts but won’t run

[RMELAN]

I’m hoping to get some help getting my old boat on the water, I’m fixing up a 1968 Glasspar with a MerCruiser 120 2.5. I got the engine running a few weeks ago after cleaning out gas tank and fuel pump. I rebuilt the carburetor changed points, condenser, plugs and coil. It’s been running great until now. When I get it stated I need to give it a lot of throttle to keep it going. It won’t idle. I also installs a new gas hose I got from AutoZone from fuel pump to carb. It is not a snug fit. I see a couple of oil drops from the hose at both the exit from the fuel pump and where it goes into the inlet on the carb. The carb seems to be fuel starved in some way. Any pointers? Thanks in advance!!

 

[Scott Danforth]

first, you cant use gas hose from autozone. Autozone does not carry the required USCG approved marine hose to prevent you from blowing up.

the line from the fuel pump to the carb should be steel or marine rated A2-15 hose. that little drip is a bomb

what is your fuel pressure at the carb. is should be 4-6 psi

if you have good pressure, it may be the inlet filter on carb or dirt in the carb
if you do not have good pressure, it may be a restriction between the pump or the tank or it may be a weak fuel pump

 

[alldodge]

installs a new gas hose I got from AutoZone from fuel pump to carb.

Auto gas line is good enough for testing but should be marine USCG type A1. Also need to fix the leak

Since your having to give it a lot of throttle to keep it running then probably need to get back into the carb, its probably flooding. Could be a spec of crud floated to the needle seat and it's not closing

 

[Scott Danforth]

AD is correct, I typed A2 vs the A1. A2 is fuel fill

 

[RMELAN]

Thanks!! I’m heading out to get USCG approve gas line. The carb was rebuilt a couple of weeks ago. Would it help if I use carb cleaner? The boat does not have a fuel filter. I’m sure it will help if I install a inline filter. I also replaced the large water hose connected to the thermostat. It had a lot of crud in it and may have gotten into the thermostat. I’m not sure if that could cause the problem?

 

[alldodge]

Look down the throat of the carb and see if you see fuel dripping. If it is, remove the top of carb, clean needle seat and reinstall.

Spraying cleaner will not clear the needle seat

A spin on fuel filter would be best, and there not that expensive

 

[RMELAN]

Thanks, what is a spin?

 

[RMELAN]

Not sure what the psi on fuel supply as I don’t have a haulage but when I removed the hose to replace it plants of fuel drained out.

 

[alldodge]

spin on canister filter
https://www.amazon.com/Moeller-0333...ne+fuel+water+separator&qid=1604159594&sr=8-7

 

[Scott Danforth]

Not sure what the psi on fuel supply as I don’t have a haulage but when I removed the hose to replace it plants of fuel drained out.

huhhhhhhh???

you will need the mercruiser fuel pump test fitting and a fuel pressure gauge

 

[RMELAN]

Wow, spell check in the wrong, it’s I don’t have a fuel pressure gauge and it has plenty of fuel. It runs now after putting a USCG hose and a spin filter on. Seems to have a small Drip of gas around the linkage somewhere. I tightened the screws on the carb and I’ll check in the morning to see if there is a still a leak. Thanks for the great tips!