Subject: Re: Vmax Fuel pump fix I took mine apart recently and had quite a bit of trouble getting those little black rubber diaphragms back into place. What you have to do is get the rubber nipple far enough through the metal washer that the rubber "shelf" on nipple catches the inside of the metal washer ALL the way around. This took careful pushing from the back and pulling with a pair of tweezers from the front. BE CAREFUL not to pull the rubber nipple off with the tweezers (since I think the rubber diaphram is worth about 10 cents yamaha will probably charge you $10 for a new one). Hope this helps Cliff >I would like to find out from other listers what they have done to fix the >Vmax fuel pump failure. I have three of them that all have the same >failure of the rubber diaphram coming loose. My question is, is there a >way to reattach the diaphram and have it stay in place? > ------------------------ From: "TC" To: Subject: Re: Fuel Starvation Message-ID: <002a01be7cfa$51ae53c0$1e00a8c0@tcamp.net> jmsmith, There is more to the fuel pump relay than is obvious. The unit monitors the same lead off of coil 3 that the vboost controller and tachometer does, (to make sure the engine is running). The reserve switch allows the unit to operate the fuel pump "after" the low fuel lamp comes on, (ground from fuel sender unit). In either case your pump stops 5-30 seconds after you are running, (this means the fuel pump relay, which is more than just a relay, doesn't think the engine is running). Replace the fuel pump relay. I didn't look at this thing but if you are seeing battery when the pump is not running, (but no current like Mike has pointed out), this is solid state .. not a contact closure. Sooooooo ... replace the fuel pump relay !! campbell (TC) ---------------------------- From: "Mike Sayers" To: V-Max@sayegh.org Subject: Re: Fuel Starvation Message-ID: <199904040054.TAA32724@smtp5.mindspring.com> On 3 Apr 99, at 19:17, jmsmith wrote: > From Mark Smith > Went out to garage today and got a large screw driver (to listen to punp > run with engine running). Turned switch on Max and pump ran for short > period as it should. Cranked bike, fuel pump ran as it should have with > speed of pulses from pump varing with engine speed (pump relay receives > input from ignition box, #3 coil I think to vary pump speed). After > about 10 min. the pump got really hot and quit running and shortly > thereafter the Max quit due to lack of fuel. As long as pump ran Max ran > therefore I believe that my problem is the pump and not the relay or any > obstructions. I'm going to take pump off tonight and try to disassemble > (if it can be). Ah HA! You have the infamous "slipped diaphragm" problem! The pump should not run continuously while the engine is running, it should only hit one stroke every several seconds. Running constantly is making it overheat & trigger a thermal cutout. Taking the pump apart is the correct solution. All you have to do is get the diaphragm back in position. Usually this is caused by a plugged tank vent making the pump pull against too much vacuum. I probably have detailed instructions somewhere in the MyList archives if you need me to hunt for them... John F is more familiar with this procedure than I am, i've never had to do it (yet) (knock on wood). ---------------------------- Merry Merry, and Happy Happy everybody! Jim (and isn't he just a Jolly Jolly Ho Ho character, huh?) John Just a little tip on the fuel pump problem. The valves inside are lightweight and come apart easily. The good news is that they're an easy fix. What happens is that excessive back vacuum from the tank (Also, check the tank for proper venting, or it will do it again) sucks the lightweight O-ring valves back through the ports. When you open the pump the rubbers should be laying inside the main body of the pump.(or part way through the port) Hope this helps. P.S. When reapplying the rubber seals, they go under the metal valves. Jim Furbur Subject: VMax Fuel Pump Question Jim, John suggested that I ask you about this. I've taken my pump apart on several occasions now, but the little rubber diaphragm seems to jump out of its retaining place pretty quick. When the fuel pump is working well, the bike is wonderfully smooth. When it is not, the bike still runs relatively well, but somewhat rougher. I'm pretty sure that the fuel tank side of the pump is O.K. and neither clogged nor kinked. I've cleaned the filter several times and have been very careful in reseating the hose. I have a feeling that the diaphragm has been compromised by existing in a folded state for a while. Are there any sources for these little rubber thingees? Any suggestions as to keeping it in place? Thanks for your help. I'm getting amazingly quick at fuel pump removal and tear down! Bill De l'Aune At 09:04 PM 1/22/98 Know what you mean Bill, I've been there! About 6 times before I got it right! The thing is , you've GOT to make sure you have it completely under BOTH the spring and the disc as well. Also, the blockage usually isn't in the feed line from the tank but in the INLET into the tank(when you're riding, fuel is drawn out of the tank creating a vacuum. The vacuum creates such draw that the pump cannot work against it and the rubbers are pulled through the small hole.) To find out if this is happening to you, either drive around a little bit, enough to draw fuel out (at least 10-15 miles) remove the fuel cap. If you hear air sucking in, your inlet is blocked. Also you can drive around w/out your fuel cap and see if the problem persists.( not highly recommended, especially w/a full tank ,haha) Jim Furbur-Lunatic Fringe Racing-WERA#594 Lehigh Cycle, Macungie, PA.610-366-VMAX(8629) Date: Friday, January 23, 1998 5:37 AM Subject: Re: VMax Fuel Pump Question Jim, Really appreciate your time and expertise. If you ever need a complex statistical analysis (my area of expertise) let me know! My gas tank cap fits very loosely, so I don't think that's the problem. I wish I could visualize what you are talking about in terms of the spring and the disk. I take the top part of the pump off (the part with the hoses) and I see a hole with a rubber disk sticking out. When I remove the rubber disk, which has one smooth side and one side with a little bump in the center, I see a silver metal disk with a center hole. This disk is spring mounted and closes against the ledge of the hole in the plastic base. I've been taking a tweezers and putting the rubber disk back in under the ledge with the little bump fitting in the hole in the metal disk. Everything moves freely and bobs in and out. I'm assuming that the rubber disk should fit between that metal disk and the plastic. I can feel the effects of a spring but can't see it. Am I in the ball park? Thanks, BILL At 06:54 PM 1/23/98 +0000, you wrote: Hey Bill. Sure wish I had an old pump here I could take apart to refresh. You should be able to take apart both sides of the pump to get @ both valves (and the spring side of the one your working on)not only does the rubber need to go back under the silver disc,the nipple needs to be pushed firmly into the center and the ring around the outside of it needs curl around the edge of the disc as well.many time it is easier to work from the back of the valve. Also, check to make sure BOTH valves are correctly in place. If one is out (the hidden one it can cause the suction to be greater on the upstream on causing it to fail. But back to the original problem the reverse suction (or gravity) should not be sufficient enough to draw even a weak rubber out of the hole it only has about 2 ft. of tube to draw up and only about a 1 & 1/2 ft. are vertical. Think of it like trying to drink out of a glass w/ a 2ft. straw. it wouldn't be very difficult and the gravity of the liquid wouldn't be very hard to hold up inside the straw.I still think you have some kind of vacuum drawing back on it causing the failure. Good luck w/ it. If your still having problem let me know, I think I may have one around. I'll open it up to go over it. Jim Furbur Date: Friday, January 23, 1998 9:49 PM Subject: Re: VMax Fuel Pump Question Jim, Thanks. They key will be getting in from the back. I've only taken the front apart, and obviously never seated the diaphragm correctly. The back pressure may have originally come from a massively clogged filter behind the pump. After my first seating of the rubber, I took apart the filter and cleaned it. After the second seating of the rubber, I took it apart again and found some additional crud. My third attempt found it almost completely clean. I think that the rubber was originally blown by the back pressure, but keeps coming out because I only had it sandwiched in between the metal plate and the plastic lip -- a precarious perch compared to your description of it being wrapped around the plate. I was not even aware of a second valve. I'll try to take it apart this weekend to correctly mount the first and check the second. The amazing thing is that the pump seems to still function relatively well in this highly compromised condition! Good design. Thanks again. I'll let you know how the pump repair works out. Bill De l'Aune Hey Bill, Just a little to explain how the pump works. it's actually a simple design that work well through it's simplicity. What it is, is basically is a canister with two one way valves and a plunger. As the plunger is actuated, on each stroke it draws fuel in one valve and pushes it out the other. That's why there should be a double barrier against flow back, and it will continue to work until both fail completely and the fuel can flow freely back into the tank @ which point it can no longer be recovered. Hope this help when you're checking it out again Jim Furbur 1/26/98 Jim, The little nipple from on the diaphragm needed to be tucked into the metal disk. I'm not sure if the edges of the diaphragm can be tucked around the metal disk. I checked by vent tube on the gas tank and it was sealed shut! Everything is put together and works wonderfully. About 3-5 clicks before start-up then silence. Bike runs smoothly once more. Thanks again. Thanks, Bill