1998 Vfr800 Not Starting

My 98 VFR800, my daily driver-commuter bike with about 45k miles, has developed an issue and I'm hoping someone might have some insight that I've overlooked.

On the way to work the other day as I was coming down the off-ramp, the FI light came on and the engine stalled. While coasting I pulled the clutch lever and tried to restart it, to no avail (starter turned, no ignition though). I ended up getting a flatbed ride home and started checking the usual suspects--fuel pump relay, main engine relay, relevant fuses, etc. I checked for voltage at the fuel pump, none, although the engine and fuel pump relays were clicking and sitting voltage was 12.1 volts. I also put the bike on the charger just in case it could be a low voltage situation but I was doubtful since it cranked so healthily. Just in case, I also put power directly to the fuel pump and it whirred solidly (and right after I plugged the harness back in the bike fired up for a one or two seconds, but probably because it had just enough fuel in the lines). I had a spare new old stock kill switch so I replaced that as well but no change. I tried a second bank angle sensor but no change. I've checked the side stand switch and that looks good (though a bit grimy).

A couple of years ago, after having dealt with far too many R/R failures I put in a VFR-ness, a Mike's R/R, a fresh stator, and a dedicated fuse block for accessories. I hadn't had any further electrical issues until now. The grounds are all tight and based upon voltage measurements and the fact that the bike cranks so well, I'm inclined to believe the issue may be the ECM/ECU or harness, though based on my research, those don't fail very often. I also checked for codes but got nothing, FI light stayed solidly lit.

Sometimes when I turn the key or toggle the kill switch (which I don't normally use) I hear the pump prime for a fraction of a second and sometimes if I toggle the kill switch to off, then hold the starter, then toggle kill to back on, I'll get a sputter (actual ignition) but no continued running and it's not consistent when i try this. I have a new fuel pump relay en route, just in case the actual installed environment is different than the test environment.

The FI light stays on when the key is turned, both the engine and fuel pump relays click (measured voltage and felt each clicking on). I doubt it would be the ignition switch since power is getting everywhere else but like I said at the beginning, if anyone has any other suggestions of something I might have overlooked, I'd appreciate hearing from you. Otherwise I'm leaning toward hitting eBay for a used ECU/ECM...

I'm surprised that the engine cranks so well if your battery has resting voltage of 12.1v. That's a good 1/2 volt low. It might be a good idea to take it to a battery shop and have it load tested. If it fails, replace it and then see what you have. If the FI light came on while running down the road, it would have set a code(s). Before going down the new ECU route, it would be good to know what the codes are and go from there.

Cogswell, thanks for the message. FWIW, I borrowed the battery from my Ducati thinking the same thing as you. That battery is 6 months old and turns over a much larger engine--no difference in cranking and the resting voltage was 12.4 as indicated on my aftermarket voltmeter. I also tried my external jumper pack and it spun marginally faster but not notably. Just checked after the battery tender sat on the VFR's battery for the day and it's at 12.8 volts. With all of these, no start.

When it happened, the FI light did come on but went solid and the bike simultaneously died, which according to the factory and Haynes manuals, can happen and would indicate any one of the original post issues.

Stays lit and engine does not start (Honda Service Manual)

• Open or short circuit at the input power line of the ECM

• Faulty engine stop relay
• Faulty engine stop switch
• Faulty ignition switch
• Faulty bank angle sensor
• Faulty ECM
• Blown main fuse B (30 A)
• Blown engine stop fuse (10 A)
• Blown fuel pump fuse (30 A)
• Open circuit in engine stop switch ground wire

Unless I'm missing something, it looks like it's pointing to either a bad harness/connector or bad ECM. Any other areas someone might recommend checking before spending loads more time & money?

I would bet that it's not a bad ECM but one of the other 9 items suggested in the service manual list.

I had an intermittent issue with a stop switch that was fixed with a disassembly and cleaning of contacts. Lots of contacts to keep clean on a 16 year old bike.

+1

Sounds like one of the following:

Main fuse holder (but you checked that right?)

Big blue connection (the grounds fail in here)

Big grey connection (the grounds also fail in here)

Or possibly the connection in between the main harness and the ignition switch.

I lost another ground on my big grey connection last week. (2007 vfr800)

[image: 38eed5071000ffaeeb59369c879b321a.jpg]

Where is the fuel filter on a '98?

On the pump, in the tank.

At least that's how my 6th gen is...

CandyRedRC46

On the pump, in the tank.

At least that's how my 6th gen is...

Yep

Quick fuel pressure test, cycle the kill switch several times listening for the fuel pump. After a couple times, you should hear the fuel sloshing back in from the fuel return from the fuel pressure regulator. If you hear that, then you definitely have enough pressure to start.

This tip is a long shot but it's also very simple. Disconnect the two large plugs into the ECU under the seat at the rear. Plug them back in. That solved a problem on a y2k I had.

All, I really appreciate the suggestions and insight. I've unplugged/cleaned/replugged pretty much every harness on the bike, tested every relay I can find (and there's no bodywork on it now so I've found a lot!). With the ignition on I've wiggled every plug connection listening for the fuel pump to spin. I think the symptoms with mine are slightly different than what most people might expect because the fuel pump does indeed come on for about 1/2 second when I turn the key or toggle the kill switch. Last night I just got 2 new OEM fuel pump relays (the same relay is used in 3 or 4 different circuits) and swapped it with no change, swapped them with others and no change.

I'll try to shoot a video this weekend because I'm not sure I'm communicating well enough exactly what's happening. If I had a bad fuse or poor ground somewhere, I don't think I'd get partial pump priming. I also broke down and ordered a used ECU off eBay and will hopefully have that early next week. I know most people think it's a long shot but at this point, I don't think I can rule it out, particularly without the ability to test mine somehow.

MaxSwell, I thought about a 'reboot' as well, left the ECU unplugged overnight too, no change.

Since you've verified operation of the fuel pump by bypassing the relay, the short duration it operates is mysterious. Here's a shot in the dark from the FSM - not sure this is it given the fuel pump behavior, but it might explain the sudden stalling.

In the FSM in the fuel section there is this passage:

"The PGM-FI system is provided with fail-safe function to secure a minimum running capacity even when there is any trouble in the system." I think it's often called "limp mode". Later it goes on though ". . . however when any abnormality is detected in the four injectors and/or the ignition and cam pulse generator, the fail safe function stops the engine from the standpoint of protecting it."

The cam pulse pulse generator shows a resistance spec of 400 to 600 ohms and both show a "peak voltage" spec of .7v min.

Of the relays, was the engine stop relay (I think also called fuel cut relay) near the rear master cylinder one of those that was swapped out (is that what you meant by fuel pump realy)?

Hi Cogswell,

Good observation on the manual. I've not begun to diagnose the individual FI components yet but that's very interesting. I did indeed replace the fuel pump relay (or as you identified, and technically correct, the fuel pump cut out relay). I'll break out the multimeter this weekend and check it out. It seems logical to me that it might take a small bit of time after getting power before the ECU/ECM then shuts off the fuel pump which would explain why it whirs for a 1/2 second after first getting switched on.

Thanks!

Bypass the bank angle sensor to test if that is the problem. Also maybe the side stand or neutral sensors.

Well, after hours of profanity, threats, and pricing out the potential value the parts of my VFR might be on eBay, I decided to print out the wiring schematic and sit at the table, not looking at the bike, and think through every bit, starting from the battery. I'm generally pretty good with electrics and electronics. I can often dive right in and identify the likely cause of it, which is part of what was driving me crazy on this one. I started by looking at the components, following looms and wiring and not working in a methodical order from beginning to end.

In working through the wiring diagram, I realized that one of the relays that I measured and found clicking correctly was not the engine stop relay, it was an aftermarket accessory relay, mounted right next to where the engine stop relay *should* have been. I jammed a shop light up into the wheel area, had my backpacking headlight on, and a handheld LED flashlight poking around before I found my engine stop relay. It was loose and sitting on top of the exhaust header. I shouldn't say entirely loose because it was partially melted to the rear exhaust header. It hadn't melted through the plastic but the rubber holster.

Once I was finally able to fish it out of there and back to where it was supposed to be, I plugged in one of my new relays, put the battery back in, and lo and behold, I had full fuel pump priming and then successful ignition!

On the positive side of it, I now have some spare parts (that I'll likely never need), have become fully acquainted with my VFRs electrics, and reminded myself of following proper troubleshooting steps.

BTW, I discovered the orange grounding block (which was in great shape), never noticed that one before.

I truly appreciate everyone's input and suggestions and insight. I kick myself for having overlooked something so simple but am grateful to have found it and learned from it all.

I posted this once before a long time ago, but it's a great bonehead story to (hopefully) make you feel better.

I think it was the VFR, maybe the RC51, but I stuck a magnetic parts dish on the tail while working on some stuff back there. Whatever I was doing required a test fire of the bike, but no fuel pump prime with key on. Took me a couple minutes, but I finally noticed the magnet was directly on top of the fuel pump relay! D'OH!