Re: 90 hp 1998 force fuel pressure at idol
Thanks
Is this something that can wait till I pull the boat out of the water for the season or do I run the risk of damaging something? based on my limited knowledge of motors I would not think leaving it would not be a problem just an inconvenience.
No sir.. Take your time with it. The fuel pump is a very simple rebuild job.. Tools are a pair of pliers and a screwwdriver, some spray carb cleaner, and a rebuild kit. A shop manual will pay for itself, but most libraries have them avalaible for checkout or in-house study/photocopying.
The job should only take about an hour and that is taking your time.
The pump is straight forward, and you'll be fine by just paying attention to removing it, and reversing the process for assembly.
Why would the fuel pump be working at higher RPM's but not at idol? I would think it is an all or nothing deal which makes me worry that it is compression because if compression is low I would think it would be the lowest at idol but gains some pressure when the engine is working harder hence no fuel pressure lost when underway.
The fuel pump may be fine, or have cracks that look like aligator hide leaking minute amounts of air, causing it to operate, but operate poorly as to starve the carbs at idle.
Or the motor might not be providing adequate compression to operate it.
OR:
It could be a partially blocked pickup tube in the carb.
It could be a leaking float needle (but you would see gas comming out of it when you pumped the bulb).
It could be that the vent on the gas tank was not venting, (but the bulb would collapse).
I was just trying to give you the
most probable causes.. Note that compression loss could be caused by any number of problems, from rings to cracked block and eveything in between. But that was why I suggested testing compression first.
With the fuel pump rebuild, about how big of a project is it? Is it something that can be don in a slip or do I need to pull it out of the water?
It can be done on the water, but you'll run the very big possibility of droppping screws, tools or diaphram over. I would wait until it is pulled out.
The kit comes with check valves too, but my experiance with this pump is that the check valves seldom fail, and are a pain to change sometimes. They have neoprene gates in them anyhow, so they are not effected by todays blended fuels. Just make sure they are clean (nothing hanging them open). They should allow air to pass only in one direction when operating right.
The biggie is that rubber diaphram.
