poor little fuel pump

Motor,’01 90 hp mercury three cylinder carbed model.
complaint,hard start and rough running when first started but seemed better once warmed up,ran decent in the mid-range but no top end power.

this came into the shop last week late,with the above description from the customer I had an idea it was running lean.
I checked the fuel hose and seen it had been replaced as it was dated 03/16/2016.
after talking to the customer a bit I found that it had been running this way for some time but he mostly putted around and didnt think it was harming anything as it did ‘run’,man I hate hearing that.

the customer also said he had been using a lot of additives,an ounce to the gallon hoping it would clear up but it never would and he finally got tired of the hard starting issues.
good thing he did as he was about to melt this motor down.

I pulled the pump and upon tearing it down my suspicions were confirmed,it was fouled with some of the remains of the old hose.
I also pulled the carbs to clean them and make sure something hadnt gotten through the filter which it hadnt yet,lucky for him.
if you look at the picture you will see the debris polluting both of the check valves in the pump,its a wonder it would run at all.
I would suggest anyone who has replaced their fuel hose recently have your fuel pump checked out for this as it wont take long for this crap to work its way through and give you fits.

this even applies to the injected models as they use a pulse pump to feed the low pressure pump on most of them.
all brands of motors can be affected by this,not just mercury.
take care of your toys guys, have a safe and fun boating season when it gets here !!

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Thanks again gpdor sharing the knowledge!

Great information!

Cringe at the thought of motor maintenance but it still is fascinating to me.

With the restriction at the beginning of the fuel process in a way, would these type blockages cause all 3 cylinders more or less burn out at the same time? Or would the starvation of fuel simply not allow the motor to get to a certain RPM to even cause damage?

Just curious man

nhamm,with a restriction like that all of the cylinders could be affected as the entire system would be lean.
a lot of which cylinder would be the first to go depends on which one is already running the hottest,in this case,the top cylinder as it is the farthest from the water pump,not always but most likely.

I have seen where the bottom cylinder will burn out first,why seeing as how its closest to the cooling water??
debris in the fuel lines at low speeds and at low fuel pressure will settle to the bottom carb before it gets a chance to get pushed any higher in the system by higher volume and pressures.

I didnt take a picture of the primer bulb,I cut it in two length wise after removing the barbed fittings,it too had a similar amount of debris in it restricting the check balls in it,why it wasnt replaced with the new fuel line is beyond me.

I will add this while I am at it,if you have a hose that fails and you find this kind of crap in it and you have installed a new hose and primer,make sure you pump out the tanks siphon tube as the debris below the primer bulb will settle back into the siphon tube.

this will require filling the tank as it will help suspend the debris in the tube and taking the motor side fitting off of the end of the hose and pumping the primer bulb vigorously while holding the end of the hose in a bucket or catch can.

I would suggest a filter in the hose before the pump but thats just another restriction the pump has to overcome and its working hard enough as it is.
once you have everything cleaned properly and with the new hose that is out that does not have a liner in it,you should be good to go.

What’s your thoughts on low permeation fuel line?

Or up sizing size of fuel hose with an inline fuel filter, the kind that let’s you see the fuel clearly? I’ve always used them and have always wondered about the restriction idea, but after years of using them I like seeing the fuel for a few reasons, but could see the reasons not to use one for restricting fuel flow.

Just out curiosity, was this on a pontoon boat?

early low permeation fuel lines is where this started,a plastic liner that was supposed to be all of that and a bag of chips,you are looking at that liner in the picture and ones I have posted in the past.
me?? no faith in anything that is supposed to be ethanol resistant,especially with the amount of additives that are oversold and OVERUSED BY THE CONSUMER,sorry,didnt mean to yell but it is what it is.

the perfect ethanol resistant fuel line would be made out of stainless steel as it is the only thing truly resistant to it,but alas,we need a bit of flexing dont we?
so the short answer is,with the stuff that is available,check it often and replace it even if the slightest question arises about its integrity.
now,convince every engine owner of any type of that.

to answer the question of see through filters,great idea but guess what??
made of plastic that becomes soft with ethanol and additive usage or worse yet,becomes brittle when exposed to the sun,not being a smart ass but can you spell fire hazard??
that,and heres my biggest objection to an inline fuel filter on the suction side of a pump,two more places where the pump can suck air for any given reason,ie,loose fitting hose from a too loose clamp,a crack in the filter etc.

two things to remember about any kind of pump whether it be water,fuel,hydraulic,etc.one,they can push a lot further than they can pull,a restriction regardless of how small can and will affect its performance.
two and most importantly,when it comes to motors and running lean,an air leak will dramatically reduce the pumps ability to draw fuel hence causing a lean condition,ever try drinking through a straw with a hole in it??
in essence,not only are you starving the motor for fuel,you are also pumping the air it takes in leaning it even farther.

I will add,an air leak on the intake (suction ) side of any pump is a bugger to find unless you go to the effort of using a piece of clear line in between any two connections until its found,a pita I will tell you from experience.
a leak on the pressure side is easy peasey as it is obvious when it occurs.

I hope you guys are learning a bit from me,I see everyday what it cost to fix things,,if you think redtail shiners are expensive at a buck a piece and they die in the live well because the water is too warm,try replacing your motor at ten to twenty grand because some entity thought it was a good idea to make fuel from food.

Denny O wrote:

Just out curiosity, was this on a pontoon boat?

no Denny it wasnt,the pontoon you saw that I was working on,it had a bad voltage regulator because the owner jumped the battery backwards,ie,positive on neg and vice versa.

the motor in question in this thread was on a pro 175 tracker.

Clear fuel filter helped me see the oil diaphragm on my VRO had a leak in er. As Sheldon stated, the fuel had trickled back in from pump with an oil hue.

Iowaboy1 wrote:

no faith in anything that is supposed to be ethanol resistant,especially with the amount of additives that are oversold and OVERUSED BY THE CONSUMER,sorry,didnt mean to yell but it is what it is.

I’ve been saying this for years, but the additive addicts are still convinced that adding a bunch of snake oil to every tank of fuel is doing something.

Well, I guess that’s kind of right. All that snake oil IS doing something–effing up your engines!

But everything gets blamed on ethanol! You guys should have been around back in the day when we actually had to figure out what caused a mechanical problem rather than just blame everything on ethanol.

Grouse

Good info!

I’ve gone completely away from permeation fuel lines and change them out often with the highest quality I can find. But I’m fairly mental with trying to prevent stuff after learning the hard way how expensive and time consuming the other route is.

I use a glass in line filter on all my outboards and rider mowers. I get the restriction issues and have come to accept the draw backs. Personal preference. If the fuel has any contaminates I can address it quickly without waiting to hear an issue.

Spot on on air leaks, small ones are the worst! Had one on my old John Deere l8O. Ended up being a fuel petcock shut off valve that was letting in a singular air bubble every once in a while, but was a bugger to solve.

Use all non oxy in everything that isn’t a passenger vehicle. Fog motors that sit and am using less and less coolaid additives. If I use them it’s a thin ratio and only to run through carbs that will be sitting idle. Use to run stuff dry/out of fuel but have gone away from that, because I think it causes other issues imo. Not gospel, just works for what I do.

Iowaboy1 wrote:

<div class=”d4p-bbt-quote-title”>Denny O wrote:</div>
Just out curiosity, was this on a pontoon boat?

no Denny it wasnt,the pontoon you saw that I was working on,it had a bad voltage regulator because the owner jumped the battery backwards,ie,positive on neg and vice versa.

the motor in question in this thread was on a pro 175 tracker.

Aha! Then that explains the Fluke of a blown fuse, tee he.