75 hp Mariner Fuel Issues

[quackerkiller]

Lately my 75hp mariner (1989 or so) had a little trouble running at trolling speeds. It would run fine, then rpms go WAY down and I'd have to choke it or it would die. It usually started right up but sometimes would be a bit of a pain. Yesterday it was running pretty well at trolling speed but on the way into the landing at 3/4 to full throttle it idled way down and died. I pumped the primer, started it and took off... same thing happend in another hundred yards or so...repeat...repeat...I had a friend keep pumping the primer when it was about to die and that seemed to work enough to get it in. The trolling and dieing was tolerable but this dieing off at higher throttle is unacceptable. What do you guys diagnose? Fuel line issue? Filter? Pump? All help is greatly appreciated!

 

[1nebel0]

Re: 75 hp Mariner Fuel Issues

Fuel pump.. easy and cheap fix... they should be replaced every couple of years but nobody does and they run for many, many , years till they strand you or you do what you did....

 

[quackerkiller]

Re: 75 hp Mariner Fuel Issues

Sounds good! Thanks for the confirmation. I will look into buying one. All I found so far is the replacement kit which looks to be a set of seals only.

 

[jimmy120]

Re: 75 hp Mariner Fuel Issues

I think I am having the same issues and all I have found for a replacement is "rebuild" kit which appears to be a set of seals. I don't see how replacing the seals will fix a broke fuel pump.

 

[jimmy120]

Re: 75 hp Mariner Fuel Issues

Lately my 75hp mariner (1989 or so) had a little trouble running at trolling speeds. It would run fine, then rpms go WAY down and I'd have to choke it or it would die. It usually started right up but sometimes would be a bit of a pain. Yesterday it was running pretty well at trolling speed but on the way into the landing at 3/4 to full throttle it idled way down and died. I pumped the primer, started it and took off... same thing happend in another hundred yards or so...repeat...repeat...I had a friend keep pumping the primer when it was about to die and that seemed to work enough to get it in. The trolling and dieing was tolerable but this dieing off at higher throttle is unacceptable. What do you guys diagnose? Fuel line issue? Filter? Pump? All help is greatly appreciated!

Did you ever fix your problem?

 

[CharlieB]

Re: 75 hp Mariner Fuel Issues

Another possibility is a poor seal at the fuel line quick connector allowing air to be sucked into the fuel system. A small leak here will act like running out of fuel at low speeds yet still allow the pump to draw enough fuel for midrange running.

This is a dangerous condition as running with partially low fuel levels in the carb leans out the fuel mioxture, raising combustion temps and possibly melting pistons.

A simple test is temporarily install a clear hose between the fuel pump and carb, run the motor and watch for any air bubbles passing thru the hose. Remove the clear hose when finished testing/repairs as this hose is NOT rated nor recommended for marine use except for short term testing.

 

[jimmy120]

Re: 75 hp Mariner Fuel Issues

Another possibility is a poor seal at the fuel line quick connector allowing air to be sucked into the fuel system. A small leak here will act like running out of fuel at low speeds yet still allow the pump to draw enough fuel for midrange running.

This is a dangerous condition as running with partially low fuel levels in the carb leans out the fuel mioxture, raising combustion temps and possibly melting pistons.

A simple test is temporarily install a clear hose between the fuel pump and carb, run the motor and watch for any air bubbles passing thru the hose. Remove the clear hose when finished testing/repairs as this hose is NOT rated nor recommended for marine use except for short term testing.

I am having a similar issue. Check it out.

http://forums.iboats.com/showthread.php?t=487181&p=3295871#post3295871

 

[jimmy120]

Re: 75 hp Mariner Fuel Issues

Sounds good! Thanks for the confirmation. I will look into buying one. All I found so far is the replacement kit which looks to be a set of seals only.

Just checking in to see if you resolved your issue yet?

 

[quackerkiller]

Re: 75 hp Mariner Fuel Issues

Sorry, I have not got to it. I hope to this week. I'll let you know how it goes!

 

[quackerkiller]

Re: 75 hp Mariner Fuel Issues

Well, I put in a new diaphram kit on the fuel pump. I took it out to Hose River in the driveway last night and it started and ran like never before...well not in the last 10 years anyway. I will put it in the water this weekend and see how it does through a full test run.