Author Topic: fuel pump problem? (Read 8085 times)

Neutron68 · « **on:** July 16, 2017, 12:19:44 PM »

I just rolled the boat out of the garage, put the water muffs on and tried to start it up.
The gas tank was about 1/2 full and had the StarBrite emzyme fuel preservative in the fuel over winter.

When I crank the starter, I'm not seeing any gas gushing into the clear fuel filter I have in line.
In the past, there are rythmic gushes of gas visible in the clear fuel filter, when you start the engine.
Could the fuel pump have failed while sitting over the winter and spring?

The fuel pump worked on the last outing last fall and has never been a problem before.

To try and diagnose:
1. To check for fuel at the input of the fuel pump, I pulled the fuel hose off the supply side of the fuel pump and a little gas dribbled out of the hose, so I believe there is gas available to the fuel pump.
2. With the idea of priming the fuel pump, I got a small funnel and filled the gas hose between the carb and the fuel pump with gasoline and tried to start it again...no change...no fuel gushing into the clear fuel filter.

I'm not sure what else to try today...

Edit:
I just talked to Joe theduceman on the phone. To test the fuel pump, he suggested getting a length of fuel line, connect it to the input side of the fuel pump and then insert it down in a gas can to see if it will pump from there.

I think my plan B will be pulling the fuel pump off the engine from the V174 I got last fall.

Plugcheck · « **Reply #1 on:** July 16, 2017, 01:41:22 PM »

I would check the fuel pump filter first, then prime the engine with a squirt of fuel, the try to start. Mechanical pumps generally don't pump much at cranking speed. The fuel in the carb bowl is used to start and run, then the pump comes into play at idle speed. Since storage, fuel in the carb well has evaporated and starting May be difficult. This is actually good, because cranking allows the engine to circulate some oil before it fires up. A couple 10 second cranks, with coil off is one of my coming out of storage tricks.

Neutron68 · « **Reply #2 on:** July 16, 2017, 03:19:40 PM »

The gas can method worked. It started and ran smoothly.

During starter cranking, I watched for fuel filter for fuel pump activity, I saw it pump 1 gush of fuel maybe 1 out of 5 cranks, then 2 out of 5, then 5 out of 5....back to normal.

I shut the engine off and swapped the boat fuel tank hose back on the fuel pump.
It started and I ran it for maybe 10 minutes at 1000 RPM, to be sure to would eventually start drawing fuel from the tank.
Is that enough time to be sure?

Suppose the fuel pump had simply lost it's prime?
Or is this a indicator that something inside is starting to fail, like the check valve in the pump is going bad?

Plugcheck · « **Reply #3 on:** July 16, 2017, 04:27:25 PM »

Sounds like fairly typical to me. All fuel pumps have a tough time pulling fuel, they are much better at pushing it. If you ran for ten minutes, you are good. The fuel in the well would likely run out in a minute or so without replenishment from the pump/tank.

Neutron68 · « **Reply #4 on:** July 16, 2017, 10:26:30 PM »

I hope this is only going happen during the first start after winter storage.
Maybe for the first start of the season I should plan on filling the carb bowl with gas using the metal tube sticking out the carb barrels and a tiny funnel?

Rich_V174SS · « **Reply #5 on:** July 17, 2017, 08:32:21 AM »

Once I installed an outboard primer bulb on the fuel hose between the tank and fuel pump. Makes priming up the carb much easier when the fuel pump starts getting weak. But in recent years when I've replaced the fuel pump I noticed they've been putting out too much pressure and causing the carbs to flood when running at idle. Just yesterday I installed a fuel pressure regulator on a guy's boat to cure that problem.

Neutron68 · « **Reply #6 on:** July 17, 2017, 08:31:42 PM »

When I bought it, this boat *had* a primer bulb in the fuel line. When Greg in New Germany swapped engines, he removed it, telling me it wasn't needed. This situation casts doubt on his statement. Should I consider replacing the fuel pump (can take pump off of V174 engine) or consider electric pump?

Rich_V174SS · « **Reply #7 on:** July 17, 2017, 09:37:29 PM »

I went electric on my V174. Installed a block-off plate on the fuel pump port and wired the electric pump to ignition through an oil pressure switch. The oil pressure switch is a safety to cut power to the pump if there's a loss of oil pressure.

Plugcheck · « **Reply #8 on:** July 17, 2017, 09:59:47 PM »

Very smart work Rich. There is a requirement in the regs somewhere I believe that states an electric fuel pump must shut off if the engine is not running, and the oil pressure switch is a great way to meet that requirement. Digging out my wire cutters right now....... Thanks for the heads up/idea Rich.

thedeuceman · « **Reply #9 on:** July 17, 2017, 10:35:39 PM »

I used this pr sw on both our boats
http://www.ebay.com/itm/Standard-SMP-PS132-Oil-Pressure-Light-Switch-Fits-AMC-CHRYSLER-DODGE-VW/152509891258?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

Sent from my iPhone using Tapatalk Pro

Neutron68 · « **Reply #10 on:** July 18, 2017, 01:50:06 PM »

Rich,

With the fuel pump in that location, it's pulling fuel out of the main fuel tank, rather than pushing fuel, correct?
Do people put electric fuel pumps in the gas tank so they push fuel, instead?
I believe most modern cars have electric fuel pumps in the gas tank.

Do the electric pumps produce more fuel pressure than the mechanically driven engine mounted pumps?
I see many pressure options in electric fuel pumps. What pressure is the ideal?
Where do you connect a fuel pressure regulator?

My engine has an oil pressure sender on it. Since the sender was wired in, I installed an oil pressure guage in one of the dash's empty instrument spots, so I can see the oil pressure. It's not been that useful, thus far.
It looks like I'd remove the oil pressure sender and put a switch in, if I wanted to add the electric fuel pump.

Duceman,

Thanks for the oil pressure switch link.

Eric

75starflight · « **Reply #11 on:** July 18, 2017, 02:30:45 PM »

Quote from: thedeuceman on July 17, 2017, 10:35:39 PM

I used this pr sw on both our boats
http://www.ebay.com/itm/Standard-SMP-PS132-Oil-Pressure-Light-Switch-Fits-AMC-CHRYSLER-DODGE-VW/152509891258?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

Sent from my iPhone using Tapatalk Pro

I better get one of these ordered for Phoenix. I have been running my fuel pump for 4 years with out one. might be a good thing to get.

Rich_V174SS · « **Reply #12 on:** July 18, 2017, 06:35:51 PM »

Quote from: Neutron68 on July 18, 2017, 01:50:06 PM

Rich,

With the fuel pump in that location, it's pulling fuel out of the main fuel tank, rather than pushing fuel, correct?
Do people put electric fuel pumps in the gas tank so they push fuel, instead?
I believe most modern cars have electric fuel pumps in the gas tank.

Do the electric pumps produce more fuel pressure than the mechanically driven engine mounted pumps?
I see many pressure options in electric fuel pumps. What pressure is the ideal?
Where do you connect a fuel pressure regulator?

My engine has an oil pressure sender on it. Since the sender was wired in, I installed an oil pressure guage in one of the dash's empty instrument spots, so I can see the oil pressure. It's not been that useful, thus far.
It looks like I'd remove the oil pressure sender and put a switch in, if I wanted to add the electric fuel pump.

Duceman,

Thanks for the oil pressure switch link.

Eric

The pump is pulling fuel from the tank, and pushing it to the carburetor. The tank is in the bow of the boat so there's a fuel hose running the length of the gunwhale. Boats do not have fuel pumps in the tank.

The pressure of the fuel depends on what pump you use. Ideally you want a low pressure pump if you're feeding fuel to a carburetor, say around 6 psi, definitely less than 9 psi. Anything more and the carburetor will flood because the fuel pressure will push open the inlet needle and float. My mechanical fuel pump was over-pressurizing causing the carb to flood. I rebuilt the carb 3 times and it still flooded. Then I saw the same problem with two other boats - new/recent issue mechanical pumps were putting out too much pressure. All the new mechanical pumps were being made in China. That's when I decided to go electric.

Link to fuel pump I'm using:
https://www.amazon.com/gp/product/B0027I88VQ/ref=oh_aui_detailpage_o06_s00?ie=UTF8&psc=1

You can get a T fitting to screw into the oil pressure port on your engine and use both the oil pressure gauge sender and an oil pressure switch. My engine just happened to have two separate ports which allowed me to keep the gauge sender in its original location.

Link to T-fitting:
https://www.amazon.com/Allstar-Performance-ALL50138-Gauge-Fitting/dp/B003C01DJC/ref=pd_sim_263_4?_encoding=UTF8&pd_rd_i=B003C01DJC&pd_rd_r=8YJG8T2MKKK58P04FMY9&pd_rd_w=juwNF&pd_rd_wg=kcOik&psc=1&refRID=8YJG8T2MKKK58P04FMY9

Neutron68 · « **Reply #13 on:** July 18, 2017, 09:59:47 PM »

Thanks for the links! Thats great!

I was going to ask what the NPT thread for the oil sender was but with the link to the T...no need. ☺

If I get a low pressure pump I guess I won't need a fuel pressure regulator? I dont have one now.

Rich_V174SS · « **Reply #14 on:** July 19, 2017, 06:44:43 AM »

Quote from: Neutron68 on July 18, 2017, 09:59:47 PM

Thanks for the links! Thats great!

I was going to ask what the NPT thread for the oil sender was but with the link to the T...no need. ☺

If I get a low pressure pump I guess I won't need a fuel pressure regulator? I dont have one now.

Shouldn't need a regulator. The only reason I used one recently was to cure an over-pressure problem with someone's mechanical fuel pump. He didn't want an electric conversion. He's an old-school guy who fears change.

BlownCV23 · « **Reply #15 on:** July 26, 2017, 06:30:47 PM »

Quote from: Neutron68 on July 16, 2017, 03:19:40 PM

The gas can method worked. It started and ran smoothly.

During starter cranking, I watched for fuel filter for fuel pump activity, I saw it pump 1 gush of fuel maybe 1 out of 5 cranks, then 2 out of 5, then 5 out of 5....back to normal.

I shut the engine off and swapped the boat fuel tank hose back on the fuel pump.
It started and I ran it for maybe 10 minutes at 1000 RPM, to be sure to would eventually start drawing fuel from the tank.
Is that enough time to be sure?

Suppose the fuel pump had simply lost it's prime?
Or is this a indicator that something inside is starting to fail, like the check valve in the pump is going bad?

The easiest way I have found to prime the fuel pump is to remove the gas cap on tank fill tube, put tape over the vent and blow air into the tank by mouth to pressurize fuel to the pump. Works like a champ without breaking any hose connections. (Just don't suck in gas fumes from the tank)

Neutron68 · « **Reply #16 on:** July 26, 2017, 06:34:07 PM »

Quote from: BlownCV23 on July 26, 2017, 06:30:47 PM

The easiest way I have found to prime the fuel pump is to remove the gas cap on tank fill tube and blow air into the tank by mouth to pressurize fuel to the pump. Works like a champ without breaking any hose connections. (Just don't suck in gas fumes from the tank)

Funny. I actually tried that. Maybe I didn't blow enough air in there?

dorelse · « **Reply #17 on:** July 26, 2017, 10:13:49 PM »

Why wouldn't the air just go out the vent?

BlownCV23 · « **Reply #18 on:** July 26, 2017, 10:31:26 PM »

Quote from: dorelse on July 26, 2017, 10:13:49 PM

Why wouldn't the air just go out the vent?

Your right, I did have to put masking tape around the vent hole

dorelse · « **Reply #19 on:** July 26, 2017, 10:56:16 PM »

Quote from: BlownCV23 on July 26, 2017, 10:31:26 PM

Your right, I did have to put masking tape around the vent hole

Cool! That makes sense!