Need Help w/Fuel Problem

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ABM-CANNIBAL · #1 Post by **ABM-CANNIBAL** » Mon Apr 10, 2006 7:17 pm

This is the first real problem I have had on this quad since I got it in late '03. A couple of weeks ago I went riding with my buddies and rode for about 45 minutes. I parked on top of a hill to watch me friend climb it. He never climbed it so I got on my quad and started it up. I tried to take off and it died. At first I thought I stalled it because of the 14 tooth sprocket I installed. Started again and the same thing. It would always start up but die shortly after. I started the quad again and looked at my fuel filter and nothing was being pumped through it. One other thing I noticed was the fuel pump didn't make the same sound when it primed. It made a buzzing sound insted of the loud weird sound that all of us are use to. I checked the battery connections and took the rear quick disconnect off and tried again. Same thing. Would start and die right after. We sat there for about 15 minutes and tried again. The fuel pump primed and I took off trying to get back to the trucks. Made it about 10-15 minutes and it died while I was in 4th gear. I ended up calling my brother to pick me up. The following weekend I took all the battery connectors off and cleaned them with a wire brush, put electrical grease on them and tightend everything up. Got it ready for the race this past weekend and thought everything was fine.

On Saturday, I ride my quad around the pits and everything was fine. We get ready for the pre-ride and take off. Ride pretty easy just to learn the track and stop for awile. Take off and about 45 minutes into the ride the bike does the same thing. One thing I do notice is right before it starts to die, there is gas like bubbling out of the gas cap hose. I ended up just getting towed by a Raptor 350.

Later that night I was able to get a hold of Canniboomer and he told me it might be the quick disconnect fitting inside of the gas tank. I should try to buy a brass fittings that removes the quick disconnect and flows right to the hose. I buy one of those fittings and connect it and everything seemed fine. One other thing, my filter in the gas tank was clean. I get ready for the race and do one lap fine, head out for my second lap in get 1/3 done and the same thing happens. It as about 45 minutes again from when I started the race till it died. Right before that happend I looked down and saw that bubbling from the hose. I didn't do that anytime on the first lap. I let it cool down for about 10-15 minutes and the fuel pump primed and I headed back into the pits and called it a day.

Can anyone help me with this problem. Why does it work fine for 45 minutes and quit. Is it the fuel pump giving out?

cannondale27 · #2 Post by **cannondale27** » Mon Apr 10, 2006 7:31 pm

There was also a factory bulletin for older style tanks with fitting at back.Fuel hose must be routed alongside the motor not over the top.Over top can cause vaporlock and just what your describing.Happens after a while since it takes a while for things to heat up enough to cause it.

ABM-CANNIBAL · #3 Post by **ABM-CANNIBAL** » Mon Apr 10, 2006 8:19 pm

Why would it start vapor locking now when it never did it before? Do you think after 45 minutes the fuel pump gets hot and shuts off and after is cools a little it works for alittle bit till it gets hot again?

cannondale27 · #4 Post by **cannondale27** » Tue Apr 11, 2006 2:56 am

Good point.Maybe the pump is on its way out.Have you checked to see if thier is air in the cooling system?Feel top and bottom hoses should both have even heat.May be overheating.

Canniboomer · #5 Post by **Canniboomer** » Tue Apr 11, 2006 3:15 am

Are you using a doo-hickey stubby for a tank vent? If so, you might try a plain tube, just to see if it makes any difference.

Hmmmn, what if a machine is running without a working vent?. The whole tank would become a greater vacuum as fuel is used up (even with the constant return). That could tend to hold back fuel as the pump is trying to draw it out ---- OK, so then what? That would cause the pump to heat up more than normal. MAJOR stab in the dark, but something to think about.

I'll delete this after you guys stop laughing!!!

ABM-CANNIBAL · #6 Post by **ABM-CANNIBAL** » Mon May 01, 2006 5:10 pm

Just wanted to post an update to my fuel problem. I looks like I was vapor locking. I re-routed the fuel line in front of the motor then to the right of it and checked all the connections to the battery and gas tank. Took it out on Friday and had no problems. I had a race this weekend and it ran perfect. Ended up getting 5th place out of 25. Only missed 3rd place by 4 seconds. Thanks for your help especially you Dave.

Josh

Canniboomer · #7 Post by **Canniboomer** » Mon May 01, 2006 5:18 pm

QUOTE (cannondale27 @ Apr 10 2006, 12:31 PM) <{POST_SNAPBACK}>

There was also a factory bulletin for older style tanks with fitting at back.Fuel hose must be routed alongside the motor not over the top.Over top can cause vaporlock and just what your describing.Happens after a while since it takes a while for things to heat up enough to cause it.

C27 nailed it for you. Great job your racing!

jwheat · #8 Post by **jwheat** » Mon May 01, 2006 7:15 pm

I know you fixed this one, but since you were thinking that the fuel pump might be acting up after it gets hot, here is a quick way to test the fuel pump(or any electrical component).

1. Use an inductive amp probe around the main power wire of the component when it is cold and see how many amps you are drawing when it is turned on.

2. Measure the amperage draw again when it gets hot. If the hot reading is more than 15% higher than when it is cold, then the component can be considered bad even if it is still operating.

i.e. 10 amps when cold
+ 1.5 amp (15%)
---------------------
11.5 amps max when hot

Note.... I just made up the amp ratings in the example to show what I meant. Don't go by these exact numbers.

Manufacturers use alot closer tolerance than 15%, so that should be the max. variance allowed.

ABM-CANNIBAL · #9 Post by **ABM-CANNIBAL** » Mon May 01, 2006 10:43 pm

jwheat, I will have to give that a shot.