225 Starves for gas after a long Idle.

[bobterisch]

Relief valve

It goes on a hose from VST into the top of air intake. Sorry but mine is a 2002, don't know if they are stil used.

[TownsendsFJR1300]

I have had one problem in ten years of using E-10 - entirely due to a 2005 era Mercury Quicksilver primer bulb hose being unsuitable.

.

When they re-powered mine in 2007, they also used Mercury Marine fuel line (from the transom fuel filter to the engine)

The inner layer fell apart and luckily, I found it in the under cowl filter while doing some basic maintenance...

Came out like mushy spaghetti... Absolute crap...

https://vid.me/JvKQ



.

[spanish sardine]

I just wanted to update. I changed the check valve right before the PST and that did nothing. I ran the boat with an extended tank to make sure the problem wasn't in the tank and I still have a problem. I also checked it before and after the filter to make sure it wasn't anything to do with the filter and problem still persist. I do believe is the low pick up pump. I am going to run it with the Yamaha computer to see what it does this week before I spend $500.00 on a pump. Check valve and installation was half of the pump price. I will report as soon as I get a diagnose

[Sailfish282]

Same Idle Problem

I have been reading these posts for months on all the forums. I have yet to see anyone say this is the answer. I have had the problem intermittently over the past 5 years. Last year I had the mid sections replaced on both engines. Since January 2017 the problem has gotten worse. I have twin F225 four strokes on my 2002 Grady White with two gas tanks. The starboard engine is the real problem child. It may idle for 30 minutes or 5 minutes and die. Both engines run great above 2000 rpms. The gas tank used does not make a difference. I replaced the Squeeze balls with OEM Yamahas first. No difference. Replaced the water separator and fuel filter. No difference. Then replaced the check valves strapped to the LP Pump. No change. Replaced the LP Pumps. No change. Replaced the check valves on the Tanks and the fuel lines from the tanks to the filter on the engine. No change. Swapped the check valve between the VST and the air intake, no change. I ran the engine at 2500 rpm, clamped the fuel line and watched the squeeze ball go flat. At an idle I can watch the bowl on the fuel filter collect air until the engine dies. The fuel flow meter shows the pump turn on and off at idle. Another thought was the fuel shut off valve. Unfortunately mine are 3/8" NPT with a bottom outlet. No one sells them unless they are 1/4" NPT. I bypassed the shut off and that didn't make a difference. I am currently replacing the housings for the water separator. The seal looks good, but it feels like it's corroded in one spot. Part of the problem is I have West Marine and a Yamaha Dealer that is more proud of Yamaha parts than Yamaha. So I have to order everything online and wait for it to arrive before I can move on to the next idea.

[rodbolt17]

my idea?
simply trouble shoot the system. you can use a vacume meter teed into the system at the pump intake.
should read at least 1"Hg and no more than 6"Hg.

[fairdeal]

It may idle for 30 minutes or 5 minutes and die. Both engines run great above 2000 rpms...
I ran the engine at 2500 rpm, clamped the fuel line and watched the squeeze ball go flat...At an idle I can watch the bowl on the fuel filter collect air until the engine dies. The fuel flow meter shows the pump turn on and off at idle.

of course the pump by design only runs 10 seconds on, 20 seconds off below 12 00 rpms.

something is handicapping the ability of the pump to keep the VST supplied unless it is running constantly (as it does above 1200 rpms)

As Rodbolt suggests, Teeing in a vacuum gauge to the lift pump will reveal a redstriction to the pump.

A length of clear tubing inserted just before the pump will reveal air bubbles if there is a leak on the suction side.

Tee in a pressure gauge on the output side to see what pressure you have while the VST is filling - and what it maxes out at when the VST is full.

With key on, the pump has power - back-probe the connector ground wire with a test lead and you can make the pump run at will.

The "check valve" is the usual suspect for this problem, but you say you've replaced that.

I didn't see that you mentioned the "F-shaped filter" between the lift pump and the VST?

You might also measure how much drains out of the VST when it has been filled (being sure to vent it with the Schrader) - it should be holding 8-9 ounces.

[oldmako69]

Here's a new LP pump....no affiliation, just stumbled across it. Might be good for a spare or troubleshooting.


https://www.amazon.com/dp/B01N22DRGR...&pd_rd_w=4WYEk

[Sailfish282]

The pump you mentioned is the one I put on. Works great. I understand I am looking for a air leak into the system. That is why I have been replacing hoses and fittings. The first thing I replaced was the check valve strapped to the pump. All of the forums call it out as a problem. I got it from Mega Zip for $60.00 plus $17.00 shipping. Yes it's an OEM Yamaha part. Ordering a Vacuum gauge to check it out.

[oldmako69]

I started at the tank and trimmed every end off every hose. Replaced all the suspect clamps.

New racor elements and took special care to insure the mating surface on the pump housing was true, smooth and free from corrosion.

If I had to pick the culprit, it was the LP pump.

Mine would run all day at speed, yet fail after a few mins at idle. I suspect that the LP pump just didn't have the juju to maintain pressure from a minuscule leak somewhere in the system.

Good luck with it.

[Sailfish282]

Well the vacuum test was a bust. At the pump the vacuum was 3hg. At the squeeze ball was the same. I did learn something. I took the hose from the check valve on the side of the pump and ran a 5/16 line back to the tank filler. The vacuum climbs to 9hg and there is a steady flow of gas back to the tank. According to fuel manager I was using 49gph. If you crimp this line you get a stream of gas from the VST vent. So the VST vent works. After this little education, I rerouted the check valve to the input of the filter. This maintained a good level in the filter. I know this is not a cure. I did a test on the check valve as well with an air compressor. I turned up the regulator on the compressor starting at 0psi. When I reached 10psi the valve opened. This means the pump output is well over 10psi. Here is something to think about. While watching the engine idle and checking the vacuum gage. I noticed the F filter. When the pump shut off the F filter would slowly drain into the VST. Could this be a problem with the float and needle valve?