Bad Fuel Pump? Viper

Here are some pics of what was left in the carb, after pulling out these screens.
 

Attachments

  • carb screens.jpg
    carb screens.jpg
    155.4 KB · Views: 28
  • carb screens 2.jpg
    carb screens 2.jpg
    153.6 KB · Views: 16
  • carb screens 3.jpg
    carb screens 3.jpg
    151.4 KB · Views: 22

Since you came this far. HERE IS A GOOD READ:
STARTRON: My bottle of Startron came w/ a little booklet. Here is, as they say: "Important Notes". During the initial treatment, sludge and other deposits that are dispersed may cause plugging or loading of fuel filters. Check fuel filters at the first sign of diminished performance and carry extra filters for convenient replacement. Once your system is clean, you filters will last longer and smoke and soot will be drastically reduced.

When I filled up, this was the first time that I put any quantity of this elixir into my tank. Had 4 gallons of gas, added 8 gallons w/ Startron. Made it 7 miles before I started to have issues. After I replace my tank line and filter, maybe I will be back in business. I am hoping that this makes sense, in that the bowls are able to fill up, but under a load, or wide open throttle, it depletes the bowls, and they are not able to fill back up fast enough, due to the plugging of the screens. If I shut it down, it is able to siphon enough fuel for the time being to re-start and idle, but not enough to make a full run, once it has started running out of fuel.
 
Last edited:
Not to hijack but I've been meaning to do my screens. How did you manage to remove the floats? I couldn't get the pin out.
 
Looks like the answer to SSBob's question is, no they did not clean the screens.

Another hat tip to SSB!

A retired engine building buddy asked me about this a few weeks back when working on his NASCAR owner buddy's '99 SRX - some may know him as the guy who wears a funny hat, races Fords and flys a plane.

Anyhow, the caretaker had already pulled the rack twice and oddly enough put some Startron in the tank. My bud called and asked about airbox removal and such, called back and mentioned that the screens were plugged.

He opened up the other '99 they had there that hadn't run right for two years and yup, plugged screens.

Even if this isn't the root-cause for the original concern, it could have been for a future burn down.

------------------------------------------------------------------------

As for getting the float pin out - I use a pair of needle nose pliers with one plier tip against the post and the other against the float pin tip, prying/pushing the tip of the float pin until it pops out.

If the above doesn't make sense or if it's a stubborn one, use a small o.d. punch and tap the pin out making sure you support the tower/post you're tapping against.
 
snopax said:
Not to hijack but I've been meaning to do my screens. How did you manage to remove the floats? I couldn't get the pin out.

I used a small nail set(punch for nailing in small penny nails below surface for trim work), and lightly tapped and they came right out.
 
Great you found your problem before it caused more serious engine damage!!! I first found these screens in the early 90s on my first VMAX4, all the Yamaha TM carbs I have opened up have these screens.
I think a lot of mysterious melt down and repeat meltdowns are the direct result of these screens being plugged.
Its seems to me that these screens could and can create more problems then they prevent as when they start to plug up they restrict fuel to the float bowls creating a lean running condition.
In my case, every time I got a new Yamaha that had these carbs I intentionally have opened up the carbs and removed these screens so they can not cause fuel restriction issues resulting in a melt down or other issues.
2 VMAX4s
2 SX tripples
1 SRX
I have never had any issues with these removed from any of my sleds since the early 90s.

JM.02c

Bob
 
Side Show Bob thanks for the insight. I just went on a quick 25 mile run, and I have NO issues. And don't count me out for not looking for some. THere were a lot of wide open throttle runs, and no hiccups. That was the cause of my grief the whole time. A little bit of money in "experimenting" later to no avail, and it was right in front of me to begin with. Maybe next time the carbs are cleaned, they really will be! I've never cleaned those screens in the 3yrs I've owned the sled, and maybe w/ the Startron it put it over the top. Just something to definately be conscious of. I was just about to have the motor torn apart thinking that it was the middle crank seal!!!

Great site and couldn't have done it w/o everyone's input.
Rick
 
Lot of good info guys, never cleaned my screens before either. Now to decide whether to clean them or remove them, especially while running these fuel sucking tripple pipes! How easy do these come out?
 
Glad its going Rick, I guess the startron really does something then, as in your previous 80 miles run it was fine then after a 4 mile run with the new stuff must have dislodged or had some reaction to whatever crud was in the system......very interesting, I am gonna do some reading on that.


maybe a new fuel filter in the tank might be a good idea as well just for peice of mind seeing how much got past it into the fine screen filters above the seats.
 
mrviper700 said:
Glad its going Rick, I guess the startron really does something then, as in your previous 80 miles run it was fine then after a 4 mile run with the new stuff must have dislodged or had some reaction to whatever crud was in the system......very interesting, I am gonna do some reading on that.


maybe a new fuel filter in the tank might be a good idea as well just for peice of mind seeing how much got past it into the fine screen filters above the seats.

Yes, I am relieved, and I have enough more than enough time into the search. I did change the in tank filter, and on the outside, it did not look contaminated, which baffles me to the extent that this sludge was able to get through the fine particle filter, and get stuck in the larger orifices of the screen. I'm wondering if it dislidged something in the pump, or if the startron dispersed stuff in the bottom of the tank, and it was at first able to liquify it enough to pass through the filter and get stuck in the carb screens. The fuel lines are only a year or two old at best.
 
02ViperMody44 said:
Yes, I am relieved, and I have enough more than enough time into the search. I did change the in tank filter, and on the outside, it did not look contaminated, which baffles me to the extent that this sludge was able to get through the fine particle filter, and get stuck in the larger orifices of the screen. I'm wondering if it dislidged something in the pump, or if the startron dispersed stuff in the bottom of the tank, and it was at first able to liquify it enough to pass through the filter and get stuck in the carb screens. The fuel lines are only a year or two old at best.

Could have been ehanol in the fuel that contributed to the screens plugging up? I have heard that this can leave a "film" on the screens and causing them to plug up?
 
I have a 2004 viper that acts similar, runs good on initial acceleration then bogs with the ECS light blinking. It seems to me that the engine is not getting enough fuel and maybe the screens are plugged under the float bowls also. We had the carbs off and cleaned the jets and shot carb cleaner through the fuel line with the bowls down to open the bowl valve and looked like good flow. We will check the screens. Another item came up with disassembly of the fuel pump, the bottom plate with the clear diaphragm has clear liquid under the diaphragm in the sensing line, this doesn't seem normal to me? Wouldn't this normally just be air that pulses with the crank pressure? I'm not sure what the clear liquid is water, fuel etc? Any suggestions. Almost seems that we may have gotten a lot of moisture through the vent? Or could the diaphragm have a small leak and getting fuel into it?
 
I have a 2004 viper that acts similar, runs good on initial acceleration then bogs with the ECS light blinking. It seems to me that the engine is not getting enough fuel and maybe the screens are plugged under the float bowls also. We had the carbs off and cleaned the jets and shot carb cleaner through the fuel line with the bowls down to open the bowl valve and looked like good flow. We will check the screens. Another item came up with disassembly of the fuel pump, the bottom plate with the clear diaphragm has clear liquid under the diaphragm in the sensing line, this doesn't seem normal to me? Wouldn't this normally just be air that pulses with the crank pressure? I'm not sure what the clear liquid is water, fuel etc? Any suggestions. Almost seems that we may have gotten a lot of moisture through the vent? Or could the diaphragm have a small leak and getting fuel into it?

check the screens but also check the float level.

the clear stuff is likely water trapped via the vent hole. the vipers seem to have a problem with that, just stick a extra washer on the studs under the pump, this will shim it up slightly and give the snow/water somewhere to escape.
 
While you are at it, replace the o-ring on there that is just above the screen. They get brittle and will do the opposite and let too much fuel in and fill your crankcase up with fuel. Another way the needle and seat can blow your engine.
 
Everything I read about the fuel pump freeze seems to address the year 2002 models, was it corrected in later years such as the 2004 as I do not see a vent hole in the bottom of the fuel pump? I talked to local Yamaha shop and they weren't sure but the clear liquid under the diaphragm in the fuel pump might be antifreeze to keep moisture out of the sensing line and also prevent it from freezing?
 
vipers chafe under the motor out to the gauge, at the stator, and under the cdi box. Might be others but any I have junked or delt with this is where the issue was.
also, for what it is worth, check your grounds.

If you can't find a cdi to try, I can send you one to try, just pay shipping, if it isn't it, just send it back.

most cdi boxes I have sold for vipers have been for flat timing, low power issue or just not running at all.
 
also, check your pulse line, if it is cracked, it might cause erratic fuel pump issues.

just throwing some darts out there for you.
 


Back
Top