help with a 1990 mercury 175hp black max

F

fishin man

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I have a 1990 Mercury 175 HP black max. Runs great sometimes and other times is stalls when running full speed. I thought the fuel bulb was going bad so I replaced with a new one, but there was no change. Can anyone help?
 
hkeiner

hkeiner

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Re: help with a 1990 mercury 175hp black max

When you say "stall" do you mean that the engine completely dies or that it hesitates but keeps running. Also, if it dies does it start up again right away or does it take a while. There are lots of possibilities out there and narrowing it down between failed spark or failed fuel delivery is a good start to troubleshooting. Providing more info will help narrow down the problem.
 
F

fishin man

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Re: help with a 1990 mercury 175hp black max

The engine doesnt cut off it just hesitates, then runs fine, then hesitates again. If I back off of the throttle the engine will idle fine. It only does this when running full throttle.
 
J

jeffdjpeat

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Mar 25, 2009
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Re: help with a 1990 mercury 175hp black max

you say you changed the fuel bulb, do you mean the fuel filter, or the primer bulb on the line?
 
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jeffdjpeat

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Re: help with a 1990 mercury 175hp black max

maybe change the fuel filter and give the fuel pump a once over, pretty cheap and good on a 19 year old motor if you havent done so already.
 
hkeiner

hkeiner

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Re: help with a 1990 mercury 175hp black max

You can use a vacuum gauge to test for a restriction in the fuel line or a failing fuel pump when the motor is hesitating. The below link contains a guide that shows how to do that. Also, you can check for a failing spark during hesitation using a timing light or spark tester. My bet is on a fuel line restriction or a failing fuel pump.


http://forums.iboats.com/showthread.php?t=265390&highlight=fuel+pump
 
C

cannonford57

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Re: help with a 1990 mercury 175hp black max

narrowing down your problem is the way to go...all the info so far is great but something as simple as hitting the primer when it "stalls"and seeing if it picks up will do a lot towards finding your problem...hope that helps and good luck
 
F

fishin man

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Re: help with a 1990 mercury 175hp black max

went through the gas line replacing fuel filter and went through fuel pump boat seems to be running great now.

Thanks for all your help it is greatly appriciated...
 
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