1988 Yamaha 130 will not run at WOT and dies ???

fishon71 · #1 May 30th, 2005, 06:58 AM

1988 Yamaha 130 wonÂ’t run at WOT. IÂ’m assuming I have a fuel delivery problem. Here is the deal. Boat had really bad gas, water, dirt and turned to lacquer and would not run. I rebuilt carbs, replaced fuel pump, cleaned filter, replaced fuel water separator, added clear view inline fuel filter, pumped aluminum tank dry, flushed tank, replaced air vent.

Motor idles okay and runs almost constantly (a few skips) okay at about 4000 rpm. It will not maintain anything much above 3500-4000. If I let is sit and idle then boot it, she cranks right up to 5900 rpm then after about 5-10 seconds drops down to about 4000 skipping and running like crap on its way down. When I first put the boat in the water after all the above work for a test run it ran at 5900 for at least 2 minutes with no problem with only about 15 gallons of fuel in the tank. Since, I filled tank headed out for a fishing run, and all this started right away. I changed plugs and it made no difference.

Okay IÂ’m looking for suggestions and have some ideas but I have a question first. If its starving for fuel would my clear glass filter show minimal fuel if it was a tank restriction? Seems level remained the same all the time. Reason I ask was I read something about an anti siphon valve on the end of the feed tube in the tank, wondering if its clogged or something if I have one.

I plan to run a separate small tank first to see what the results are bypassing everything before the engine.

Any other ideas? Does it sound like a fuel delivery issue?

Thanks

Ray Neudecker · #2 May 30th, 2005, 08:08 AM

It does sound like a fuel restriction. The seperate tank will help to determine the location. The anti siphon ball is located in the tank fitting where the hose hooks up. Bypass the fuel line to the engine connector and also the engine mounted filter. The bracket or filter holder has been a source of restriction where the motor has sat for a long period and will drive you crazy since the filter itself will seem ok.

fishon71 · #3 May 31st, 2005, 10:46 AM

Well, I bypassed built in tank with auxiliary tank connecting directly to fuel filter in the engine. Even though it seems slightly better and would maintain 4500 rpm is still dies at WOT and runs like crap above 4500. If I boot it from a stand still it cranks to 5900 and in a few seconds starts to fall back quickly pulsating and skipping. Should I go directly to the carbs with fuel? When I rebuilt the carbs I didnÂ’t measure or check float height, I would think they rarely would get messed up, but could be ??? What do the needle valves adjust? Do they have anything to do with WOT?

WhatÂ’s next?

fishon71 · #4 May 31st, 2005, 06:00 PM

Among my other questions, I meant what does the pilot screw adjustment do for each carb? Does it have any effect on WOT? Reason I ask is, it was out further prior to rebuild but I set it per the service manual spec. Its only slightly different.

fishon71 · #5 June 2nd, 2005, 04:07 AM

Had to pick up some parts yesterday at dealer, while there mentioned my issue to the head mechanic. He believes its the carbs and mentioned - since the needle valve seat is not serviceable on these carbs and the channels that feed it can get clogged and there is no way to clean other than drilling out old seats and some how replacing from another old carb. Does this make sense? How about an electronic (electrolysis) cleaning of these carbs? Or am I barking up the wrong tree?

Ray Neudecker · #6 June 2nd, 2005, 05:11 AM

I haven't tried electrolsis, but first I would disassemble carbs and soak overnite in carb cleaner. After that and cleaning out with hot water and blowing all passages with air, do a flow test. Hook a piece of hose attached to a faucet to the intake of the carb with the needle and float removed. Turn the water on with the carb upside down until you have about a 12 inch spray. Shake the carb and move around to see if the spray deflects to the side. If not you are most likely OK. If it deflects you still have a restriction. If not you should be ok with a new needle and kit.

fishon71 · #7 June 2nd, 2005, 06:04 AM

Okay I'll try this.

Do I buy a gallon of carb clean or what?

When you say clean with hot water, like dunk them in boiling hot water and blow with compressed air or what?

For the water test, what do you mean by intake? The fuel inlet line where the fuel hose hooks up? Water on full blast or turn on slowly to get about 12" spray out?

Thanks

fishon71 · #8 June 3rd, 2005, 07:30 AM

I managed to find a gallon of carb soak, wasn't easy, I will proceed this weekend.

fishon71 · #9 June 4th, 2005, 04:46 AM

Okay disassembled and soaked carbs in carb cleaner overnight.

Washed with hot water and blew out with compressed air.

Garden hose water test shows minimal flow in one of the float seats, I canÂ’t get in there to clean or seem to blow free.

WhatÂ’s next?

fishon71 · #10 June 6th, 2005, 04:59 AM

Well, I kept flushing, probing and blowing, I think I might of cleared the obstruction because I have good water flow out of both seat holes now. I put carbs back on engine and started in yard, will be a while before water test can be done.

Pretty neat trick that water flow test, thanks!

fishon71 · #11 June 13th, 2005, 05:46 AM

Okay got 5800 constantly running on external and internal tank. One new problem though. When I changed from external tank that was hooked directly to fuel pump to internal through connectors on engine we got NO gas at all. Seems the connector on the end of the hose to the one on the engine was completely restricted. I did clean both these items male & female and it worked before I did so. When I bypass and hook internal tank directly to fuel pump she was fine.

Is one of this items more prone to failure than the other or should I just replace both male & female. I think there is a check valve in one of these items, could be bogus. I bet the engine mounted male part is costly.

Ray Neudecker · #12 June 13th, 2005, 08:04 AM

Do like Yamaha and bypass the fuel disconnect. Bypassing the fuel filter mounted on the engine is something I reccomend also on those older models. Install a Water seperator filter in the line instaed of using the factory installed one on the engine.

fishon71 · #13 June 13th, 2005, 11:56 AM

Good idea why didn't I think of that - just get rid of the extra hardware, I have no need to disconnect from that point anyway, save money too!

What wrong with the engine mounted screen/filter?

This is a fixer upper boat and it aint gonna be perfect, just as long I can go fishen and return!

Ray Neudecker · #14 June 13th, 2005, 04:33 PM

They seem to develop a restriction if allowed to sit for extended periods of time. The restriction is in the housing. Later models have a much larger housing and fitting. You did the right thing on cleaning the carbs. Perseverence is the key with that type of problem. At least with the water hose test, you know when you have it cleared.

fishon71 · #15 June 14th, 2005, 04:54 AM

Why do you think I got 6000 rpm for a few seconds before it started to die and now only 5800 with carbs cleaned/soaked and seems to run well at that. I know I'm in the range and 5800 is fine, just currious how I got 6000 when things were not right.