93 (86) trx 350D fuel pump voltage reads 5volts

1626 Views 11 Replies 2 Participants Last post by Voltron, Oct 5, 2019

Voltron

Discussion Starter · Oct 2, 2019

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

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Goober

· #2 · Oct 3, 2019

Voltron said:
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

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Goober

· #4 · Oct 4, 2019

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.

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Goober

· #5 · Oct 4, 2019 (Edited)

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

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Goober

· #7 · Oct 4, 2019

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

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Goober

· #11 · Oct 5, 2019

Voltron said:
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

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