P500 Pioneer 500 No Go No Mo...

[bigbore]

As remarked in my "Ben A Whey" post, I went on a 3 hour ride, parked the buggy for about 6 weeks and when I went to run it, it popped once and did not start.

I'm using a Honda TRX500 manual as a guide, the engine seems to be almost identical to the Pioneer's.

I had a flashing engine light which flashed 2 slow, 3 fast. I checked my fuses and had a blown 10A pump fuse. I swapped it and the engine error light stopped. I also had a service interval wrench1 which I cleared. If I step through the screens on the display it still appears with the hour/mileage count but doesn't show on the start screen when I first turn on the ignition.

I pulled the plug after cranking a few times and it looks dry. The spark looks good being clearly visible when I lay the plug against the cylinder head and crank.

I'm headed into the gas tank. I can't hear the pump prime when I first tun on the ignition. Normal? I've removed all of the molded panels underneath the seat and cleaned it up for disassembly. Unless I'm mistaken --I'm looking for guidance here -- the fuel pump is inside the tank. I pulled the pump electrical plug, turned on the ignition and am getting 11+ volts on the white wire with the blue stripe using the green wire as ground. No voltage on the other two wires.

Comments?

 

[Admin]

 

[ByronM]

What is your battery voltage and what is it while cranking it over?

 

[70Bones]

The white/blue wire is for the fuel level gauge. You should have 12 volts on the brown wire, if not, don't bother pulling the pump. The brown wire gets its power from the fuel pump relay, one of the 4 relays in the upper right side of the battery box. Try swapping those relays around and see if the problem moves to another issue. They are standard automotive relays, you can get them at your local car parts store.

 

[bigbore]

What is your battery voltage and what is it while cranking it over?

I didn't check the battery voltage. I have seen suggestions online that low voltage might prevent starting but after finding the blown pump fuse and confirming spark I figured there was a pump problem which blew the fuse. I'm putting a jump boost pack on it while I trouble shoot so I don't kill my battery so I suspect it is 12+ volts.

 

[bigbore]

The white/blue wire is for the fuel level gauge. You should have 12 volts on the brown wire, if not, don't bother pulling the pump. The brown wire gets its power from the fuel pump relay, one of the 4 relays in the upper right side of the battery box. Try swapping those relays around and see if the problem moves to another issue. They are standard automotive relays, you can get them at your local car parts store.

I'll bet you nailed it. As much as it sits, stuck relay sounds like a good hypothesis.

Should I be able to hear the pump prime when I turn on the ignition?

I'll be very busy for almost a week but I'll definitely let everybody know what the problem was when it is resolved, even if it means a trip to the dealer.

 

[70Bones]

Yes, you should hear the fuel pump run for a few seconds until it build enough pressure to shut off.

 

[bigbore]

Update:

I finally had some free time to continue troubleshooting my no-go problem. As suggested I went for the relay block(?).



The block is held in place by a nylon clip that attaches to the back of the electrical box. This is a pictue of the clip from the drivers side with the seat pans removed looking across the top of the cylinder.



I had to mangle the clip, it was in an area that is difficult to access and I wasn't familiar with this style clip so it will need to be replaced when I fix the P500. It should be squeezed from the top and bottom.

Relay block is free. I eventually removed the battery to give better access. I'll test and swap them time permitting. Sliding the relay block straight out, anybody know their functions top to bottom, left to right?




Single relay. They look like good quality relays, copper prongs, potted and made in Japan. "Omron" brand.



Hacked clip and the blown 10A fuse.

 

[bigbore]

Update 2:

I setup a relay test and bought a replacement relay at Advance Auto Parts. The replacement part was not Omron brand and was $14. I probably could have sourced it for ~$10 online IIRC but I wanted to compare with the original and be able to deal with the vendor 1 block away.



The replacement part is dimensionally identical as you would expect.



I tested both relays with a benchtop power supply and multimeter. The Honda Omron relay seems to be polarized, latching only with the leads connected one way and using 80 mA when latched at 12 volts. The Intermotor relay is not polarized, latching with the leads in either direction -- which is consistent with videos I watched on YouTube -- and used ~130 mA when latched; note the symbols on the relays(resistor vs diode). Both relays latched down to 9 volts.

 

[oldfortyfive]

Did the aftermarket relay work?

 

[bigbore]

It has been like this for 5 days so I don't know yet. No garage.🌂

Also, I haven't found the bad relay, the relay I pulled(upper left) seems good. 3 to go.

 

[bigbore]

Update 3:

We finally had a day without rain today so I went back after it.

All relays tested good. I cracked the case of one of the relays pulling it out for testing so the spare came in handy although I would have preferred to keep them all OEM.



I'm still not getting any voltage on the brown wire. I rechecked every fuse including the main 40A and battery charge which were all good. I'm checking the voltage on the plug leads using the green wire as ground for all of them. I'll try to use the white wire as a ground for the brown next go-around and if I still come up with no voltage I'll start tracing from the battery forward.



Any schematics out there? I searched and could only come up with the Honda 500 quad that uses the same engine and is similar but not exact.

 

[HondaTech]

Update 3:

We finally had a day without rain today so I went back after it.

All relays tested good. I cracked the case of one of the relays pulling it out for testing so the spare came in handy although I would have preferred to keep them all OEM.

View attachment 204967

I'm still not getting any voltage on the brown wire. I rechecked every fuse including the main 40A and battery charge which were all good. I'm checking the voltage on the plug leads using the green wire as ground for all of them. I'll try to use the white wire as a ground for the brown next go-around and if I still come up with no voltage I'll start tracing from the battery forward.

View attachment 204968

Any schematics out there? I searched and could only come up with the Honda 500 quad that uses the same engine and is similar but not exact.

The brown wire feeds only the pump from the relay
Green is ground
Light blue is the meter feed ground
White/blue is the meter feet hot

Have you tested for continuity from the relay side to pump side of the brown wire?

 

[bigbore]

Have you tested for continuity from the relay side to pump side of the brown wire?

No, I don't know which relay is the pump relay. When I get back after it next week I guess I'll just have to check them all.

 

[HondaTech]

Here is a screenshot of the relay wiring for a 2015, wasn't sure what year you have.

 

[bigbore]

Here is a screenshot of the relay wiring for a 2015, wasn't sure what year you have.

View attachment 205003

Thanks. 2015 is my model year.👍

Another mistake I may be making is not having the meter attached when I turn on the ignition, I turn it on and probe leisurely.

From the Honda TRX 500 Service Manual:

 

[bigbore]

Update 4:

I finally got some time to continue troubleshooting.

I was getting 11.7 volts at the plug for ~2 seconds. I could barely hear the fuel pump, the sound reminded me of an RC servo.

I guess the next step is to disconnect the fuel line, put 12 volts on the tank receptacle leads and see how much fuel it pumps. The manual for the TRX 500 has a described specification.

 

[bigbore]

Update 5:

I pulled the fuel line off of the tank and turned on the ignition, no fuel came out of the tank hose attachment fixture. I turned the key to the start position turning on the starter and still no fuel. At this point I'll assume a blockage at the very least with a failed pump worst case. A failing pump, for whatever reason--blockage or seized--would probably explain the blown fuse.

 

[bigbore]

UpDate 6:

Out! It was a tight fit, I had to spin the assembly as I was extracting it to clear a seat pan support bar directly over the pump assembly. You have to be careful not to bend the gas tank level float arm; I probably will have a slightly longer range with a slightly smaller reserve. Spinning/unlocking the assembly retaining ring was tough!

I'm out of time for two weeks. Stay tuned.

 

[bigbore]

Update 7:

I touched 2 bare wires with 12 volts supplied to the pump leads and the pump seems to work fine, purring smooth and quiet. According to the manual I'm using I should do a flow test. I need to get some 2mm crimp leads and some fuel line to return the pumped fuel to the test tank, I don't want sparks arcing while I pump fuel all over the place. Hopefully I'll be able to test tomorrow, if not, next week.

 

[NTCPrezJB]

Sounds like you are progressing through your troubleshooting.