1982 Mercury 7.5 hp - hard starting - once started runs great

[fishon71]

Carb has been pulled apart soaked, blown and cleaned - I pull & pull it will not start. I give it a tiny squirt of starting fluid it starts right up and runs great. Once warm it will start first pull every time - any idea why it will not start the normal way? Compression is a little low on the top cylinder - maybe 95 psi bottom is 140, I know that's quite a span but it run great once started.

 

[jerryjerry05]

Re: 1982 Mercury 7.5 hp - hard starting - once started runs great

That much difference is probably your problem.Do a GOOD decarb with Mercurys Power Tune or Seafoam.Try to bring the #s up.J

 

[jbjennings]

Re: 1982 Mercury 7.5 hp - hard starting - once started runs great

Carb has been pulled apart soaked, blown and cleaned - I pull & pull it will not start. I give it a tiny squirt of starting fluid it starts right up and runs great. Once warm it will start first pull every time - any idea why it will not start the normal way? Compression is a little low on the top cylinder - maybe 95 psi bottom is 140, I know that's quite a span but it run great once started.

I agree, 95 and 140 is a HUGE difference. It runs good at WOT without any knocking and has good power??? Strange, indeed.
I'd also watch the choke plate while pulling the choke and making sure the plate is absolutely closing all the way. If not, it'll do as you describe because it doesn't suck enough fuel in.

 

[fishon71]

Re: 1982 Mercury 7.5 hp - hard starting - once started runs great

Okay, the choke was the answer, just had to tighten it a smidgen and now it fires up like it should - thanks for the advise