Mercury 900

[79camaro]

So we finally got our 78 engine running after rebuilding the whole electrical system. We had her out and after a little starter fluid (yeah I know we aren't supposed to use it) she ran on one tank. When we switched tanks she died and we can't figure out whether it's just air in the fuel line or are we missing something? Thoughts? She sat for 3 years so possibly the carbs need to be cleaned?

 

[Gomer50]

Re: Mercury 900

Make sure your fuel tank vent is open,fuel lines in good shape,when pumping the bulb will the bulb stay hard for awhile,On top of the fuel pump is a round inlet cover that has a screen in it make sure its clean (possible fuel pump rebuild).Spray some 50:1 gas mix in the carbs to see if she fires up.If she fires up its not electrical.Maybe a good carb cleaning is in order also.

 

[79camaro]

Re: Mercury 900

Thanks Gomer. It ran for a bout 30 minutes without an issue. I switched over tanks and she wouldn't start. I killed the battery (and a can of start fluid) and had to be towed by a jet skier I also sprayed some gas into the carbs and no go. We did adjust the timing a tiny bit before we ran her, and it seemed to be ok. Strange how she ran fine on one tank and not the other.

 

[Gomer50]

Re: Mercury 900

If you wasted a can of starter fluid and she wouldnt fire,you might want to check to see if you have spark.If you dont have spark there are a number of things that can be wrong. Do you have 12 volts on the red and white connectors on the switchbox side with the key in the on postion? Check back.

 

[79camaro]

Re: Mercury 900

Yeah shes got spark, I am thinking it has to do with the fuel line. The primer pump feels like it has air in it, but when I pull the fuel line there is definitely gas flowing. I'll clean the carbs today and see what happens. Thanks!

 

[Chris1956]

Re: Mercury 900

If you sprayed starting fluid into that motor and could not get that engine to fire, you either have no spark or no compression. if you spray starting fluid into a cranking motor, normally they catch on fire, so consider yourself lucky...

 

[79camaro]

Re: Mercury 900

No I didn't spray it with fuel when it was cranking, just put some in the carbs as it was getting spark but didn't seem like it was getting any fuel. What's the best way to get the air out of the fuel lines?

 

[79camaro]

Re: Mercury 900

So we took the carbs off and they were spotless. Checked the timing and buttoned it back up. Tried our best to bleed the fuel line (as I really think this is the issue) and she started after a few squirts of starter fluid. It seems to be running ok, but still wondering how to keep air out of the line is it is really the heart of the issue.

 

[Gomer50]

Re: Mercury 900

IF You dont quit using starter fluid your gonna have alot more problems than air in the fuel line.Do yourself a big favor and buy yourself a real primer bulb cost a little more but hey its worth it and you might want to try bypassing the fuel quick disconnect on the motor.No hate or discontent intended but using starter fluid will put that motor in the junk yard..

 

[79camaro]

Re: Mercury 900

Well it has a primer pump but it just isn't doing the trick, on shot of start fluid and now she starts right up. So not sure where to turn next?

 

[Gomer50]

Re: Mercury 900

Thats exactly what I am saying primer bulb isnt doing the trick.Inline 6's need to be choked and primed so that gas is almost squirting out of the carbs almost impossible to flood.They love fuel.Also make sure your cold start lever on your remote control is in the wide open position.When you pump the primer bulb can you squeeze it hard enough to get fuel to come out of the carbs?

 

[79camaro]

Re: Mercury 900

Cold start level is operational, I suspect the bulb maybe? I can hear some air when pumping and it definitely doesn't feel full. Will switching that out add air into the fuel line? Is there an easy way to test that?

 

[Gomer50]

Re: Mercury 900

I think you just answered your own question.When you switch the bulb out there will be air in the fuel line,but after you install the new one and pump it up the air gets pumped right out of the carbs.Once the carbs are full the float shuts off any more fuel until needed.If the bulb is full it will be tight and should stay that way for some time (if no air leaks are present within the fuel supply hose).Believe me been there done that,can get really under your skin and alot of bad words.

 

[79camaro]

Re: Mercury 900

Thanks a ton! I am going to try this tomorrow morning, I'll let you know how it works out.