[Voltron]

Hello, I have a Canadian 93 trx350 D. I have back tested all the pump and relay connections. All test 12v except relay to pump test 5v when cranking. The bike runs good but stalls when ideling. The pump bench test good works well directly to 12 v but doesn’t always supply fuel to the carb and bike dies. Is this the relay causing problems? (Back story) bought the bike used and it ran well until the pump started acting up, I have removed the fuel tank and cleaned 26 years worth of rust out of it, I am now cleaning the carb. I have not put it back together yet so can’t test the pump with the bike running, cranking produces 5volt at pump/relay connector

 

[Goober]

Hello, I have a Canadian 93 trx350 D. I have back tested all the pump and relay connections. All test 12v except relay to pump test 5v when cranking. The bike runs good but stalls when ideling. The pump bench test good works well directly to 12 v but doesn’t always supply fuel to the carb and bike dies. Is this the relay causing problems? (Back story) bought the bike used and it ran well until the pump started acting up, I have removed the fuel tank and cleaned 26 years worth of rust out of it, I am now cleaning the carb. I have not put it back together yet so can’t test the pump with the bike running, cranking produces 5volt at pump/relay connector

Is it an OEM pump?
I think you can do the flow test without the carb
I think your carb is the problem

 

[Voltron]

Thank you goober. I have not yet done a flow test. The bike is starving for fuel but only after riding for a while. It starts and runs at idle all day, once we go for a ride the bike stalls at idle but starts and runs again, eventually though it will choke out and the pump can’t pump hard enough to get fuel to the carb. I can see it bubbling in the tube and hear it pumping. The carb also has no response to adjusting the idle speed screw, potentially a separate problem. I believe it to be that periodically the pump doesn’t receive enough voltage to pump fast enough maybe. I am not to sure. I am cleaning the carb tomorrow and reassembling the system . What are your thoughts? Also I don’t know if the pump is oem . I bought it used the tape around the contacts looks newer than 26 years old, it’s most likely a replacement

 

[Goober]

Is the fuel tank rusty inside?

Here’s what I would do. You’re rebuilding the carb right? Do an extra good job of cleaning all passages ( i use pipe cleaners cotton swabs and dental brushes and Berryman Chemtool). Replace the starter valve AKA choke valve (gasket should be pliable and conically shaped pointing into the bore).

I would perform the fuel flow test. In ON and RESERVE. If it’s slow then it could be rust/seds clogged the intake tubes (clear them with an old cutoff brake cable), dirty fuel filter, cracked feed lines or slipped gasket in the petcock. You can actually peer into the back of the petcock.

 

[Goober]

Fuel tank repair thread

86 TRX350 Fuel Tank Borescope

Hi bought a cheepy borescope for $20 about 2 years ago—I scratched the lens pretty bad, but it works better than nuttin The attached pix are from an ‘86 TRX350 tank—showing the interior plumbing and the screens built onto them. First is the reserve pipe with the drain bolt removed; 2nd is the...

www.hondaatvforums.net

Petcock repair thread

Petcock Rebuild III 86-89 TRX350

Update of petcock rebuild procedure 86-89 TRX350; this is my seventh one—sofar I have only found one oddball with a lever that was slightly larger diameter. You can buy a set of seals on fleabay that includes the 4-hole packing, an oring lever seal, 2 tank seals and 2 screws. It will help...

www.hondaatvforums.net

BTW your model is more like an 88-89 model not an 86—some parts will interchange but others esp electrical will not work and may damage other components. Just know this is while you’re doing repairs

 

[Voltron]

Thank you for your help goober, I have cleaned the fuel tank. It was full of rust and sediment, I will be doing a carb clean today and flow test as well once I put the tank back on the bike. The petcock is clean and seals are good. The honda techs at my dealership are saying that the voltage at the pump should be 12 volts. I will do a flow test with the pump hooked up and then with it connected to a 12 volt supply to see if there is a difference. Great advice by the way, thank you for the model compatibility update, i will report back after it is reassembled, when the bike was running the idle adjust screw had zero response, I want to see if the recent work makes a difference

 

[Goober]

Carb synchronization is very exact on the QA03A. Before you reinstall set the throttle valve adjustment (service manual). Set the idle adjustment to zero—barely touching throttle valve mechanism

Check to see the pilot screw port is clear (tip of old pilot screw not broken off in there.

After reinstall take all the slack out of the throttle cable—get the hand throttle adjustment screw in the middle so you can adjust tight or loose cable at the handlebar. Check to ensure the throttle valve opens the instant you roll the throttle

Then start tightening idle adjustment screw

 

[Voltron]

Thank you for your help ?. I am just getting into the shop now and putting the tank back on for the flow test

 

[Voltron]

Flow test produced twice the fuel amount when connected to straight 12 volt supply

 

[Voltron]

So far after cleaning the fuel tank, changing fuel filters, cleaning fuel lines and carb and making the recommendations for carb adjustments the bike still stalls after initial start at idle after riding 2 minutes, also the choke functions properly but stalls the bike when open and the idle adjustment screw has no effect. The fuel cut off relay tests 9 volts at the pump connector while running. I think it’s faulty, however when the pump is connected to straight 12 volt supply it pumps more fuel then when connected to the relay.... that being said the bike still performs the same whether the pump produces 12 or 9 volts at the pump, I performed a test bypassing the relay. What are your thoughts???? Could the pump be faulty and the relay? Or is there something else causing the bike to die when idling???

 

[Goober]

So far after cleaning the fuel tank, changing fuel filters, cleaning fuel lines and carb and making the recommendations for carb adjustments the bike still stalls after initial start at idle after riding 2 minutes, also the choke functions properly but stalls the bike when open and the idle adjustment screw has no effect. The fuel cut off relay tests 9 volts at the pump connector while running. I think it’s faulty, however when the pump is connected to straight 12 volt supply it pumps more fuel then when connected to the relay.... that being said the bike still performs the same whether the pump produces 12 or 9 volts at the pump, I performed a test bypassing the relay. What are your thoughts???? Could the pump be faulty and the relay? Or is there something else causing the bike to die when idling???

No I’m not sure the pump or relay is faulty although don’t rule it out yet.
How does the choke plunger (enrichment valve) look? Is the seal conically shaped and pliable or is it rounded and stiff? New one needs to fit in the bore with no slop

 

[Voltron]

The brass is flat on the bottom and the o ring is tapered, I have not rebuilt the carb just cleaned and reassembled, the fuel tank was rinsed with a baking soda solution. I am spending the $100 to replace the relay in hopes it solves the supply problem, do you know what may be causing it to stall and have no response with the idle adjustment screw?