5th gen doesn't start because fuel pump won't run

[shad68]

I bought a '98 5th gen VFR 800 two months ago, in part due to the reputation for bullet proof reliability. But it's already left me stranded on the side of the road and won't run anymore. 🥲

 

But anyway, what happened? I was out for a ride and just after overtaking a car and pulling back into my lane the engine just died. At first I though I had just run out of fuel, because the fuel gauge displayed 3 of 8 bars for a while and then suddenly refreshed to the last blinking bar when I was stopped at the side of the road. But even with some fuel back in the tank it didn't start.

 

The symptoms

- when I turn the ignition on FI and CEL are permanently on (not sure if this is normal behavior or if they should go out after a couple seconds)

- the fuel pump does not prime when ignition is turned on or the killswitch is flipped from off to on

- on starter button push the engine will crank (but no combustion without fuel, obviously)

 

Diagnosis so far

- I ruled out the side stand switch, lean angle sensor and other lockouts like that, because if those were triggering the starter wouldn't crank

- all fuses (including the 30A main fuse) are fine

- other electrics like dash display, indicators, horn etc. are working

- went through the procedure to check the FI error codes, but there were none. Just the FI light solidly on.

- no voltage at the fuel pump plug (when I turn the ignition on), but fuel pump runs when I apply 12v directly to the contacts

- no voltage at the fuel cut relay, but relay audibly switches when I apply 12v directly

- there is no voltage on the black/brown wire going from the fuel cut relay to A5 on the PGM, but multimeter shows continuity between those points

- there is no voltage on the black/white wire connecting B8 on the PGM to the fuel cut relay, engine stop relay, ignition coils etc. etc. But I confirmed continuity between B8 and the two relays as well as the ignition coils (also checked the plugs on the coils). Didn't check the injector or from the other side of the circuit at the main fuse yet.

- I checked the notorious ground connector, but it seems fine. I confirmed continuity between each individual incoming wire and the grounding point on the frame, so I left it alone for now.

- After all the above I thought the PGM itself might be defective, so I got a replacement but that didn't change anything either.

 

I'm at best a layman when it comes to electrics, so all of this has already been way past my comfort zone. I'm way beyond being at my wits' end and absolutetly stumped. Any help you guys might have would be thoroughly appreciated, right now I just feel like a massive idiot who burned a bunch of cash on an (admittedly awesome) bike that's (for me) unfixably broken after barely two months.

[bmart]

What is battery voltage with key off and on? 

[Grum]

You sure have been busy. Excellent write up, you have done a great job in checking things, you MOST CERTAINLY are Not "a massive idiot".

 

You just needed to stay focused on that Black/White wire no voltage issue! You've found the problem but not the cause!

You need to follow the loss of power (step by step) on the Black/White wire back to it's source. Following the path of the Black/White by measuring its voltage (or lack of voltage) back from the Engine Stop Relay Black/Pink wire to the fuse box Fuse B then the Red/White wire back to Main Fuse B and then ultimately the Battery. This should identify the cause.

 

- With Ignition to On you must have Battery voltage on the Black/White wire feeding all the EFI stuff. The Fi light permanently On is an indication of a loss of this power. Fi light should normally be out after the 2 to 3sec Fuel Pump prime.

What is the CEL light you mention??

 

- Check the Main Fuse B 30amp next to your Starter Relay have a very close inspection of it as it can suffer badly from overheating, burnt wiring and high resistance connections, it's a common but not solely the cause of the fault you have, see attached picture.

This fuse is the main power source for all your EFI stuff, it feeds sub fuse B 20amp in the fuse box.

If the Main Fuse B 30amp and its wiring check out OK your fault may be as simple as a faulty ESR.

 

- Does the ESR energise at switch On?

Probing the relay wires. What voltage do you read at the Black/Pink wire of the Engine Stop Relay with Ignition Off and On, should be battery voltage in both conditions? At switch ON and Relay energised the voltage should transfer to the Black/White wire.

 

Note for info - Confusing issue regards the Engine Stop Relay (ESR).

The Black wire feeding its coil is Positive +12v while the Red/Orange wire for the coil (from the Engine Stop Sensor or Bank Angle Sensor) is the Ground/Negative for the coil! Seems to go against assumed wire colour code conventions.!

 

Check this and get back to us. Step by step we should hopefully have your problems solved!

 

 

[shad68]

Wow, thanks for the detailed reply! ❤️ After posting yesterday I stared at the wiring diagram some more and finally felt like I was making some progress understanding the whole wiring setup for the fuel system (power from fuse B through bl/p wire to ESR, through bl/w wire to FCR and everything else on that circuit). So it's really good to see you confirm my read - and add on it.

I was already thinking I should start trying to trace the fault from the start, where the power comes in. But I don't think I realized the connection to main fuse B yet... and I think I might have overlooked it when checking the fuses, too (was a week ago already so not entirely sure).

 

I'm a bit pressed for time this weekend but I'll try to find a moment to check the things you mentioned.

[Grum]

On 6/30/2023 at 4:25 PM, shad68 said:

Wow, thanks for the detailed reply! ❤️ After posting yesterday I stared at the wiring diagram some more and finally felt like I was making some progress understanding the whole wiring setup for the fuel system (power from fuse B through bl/p wire to ESR, through bl/w wire to FCR and everything else on that circuit). So it's really good to see you confirm my read - and add on it.

I was already thinking I should start trying to trace the fault from the start, where the power comes in. But I don't think I realized the connection to main fuse B yet... and I think I might have overlooked it when checking the fuses, too (was a week ago already so not entirely sure).

 

I'm a bit pressed for time this weekend but I'll try to find a moment to check the things you mentioned.

 

Good luck and keep us posted. I'm sure it won't take long to find the problem...............maybe!

[shad68]

Come to think of it... son of a... the head light is also powered through main fuse B, and I think that might not have been working either when I checked the other electrics (again not entirely sure), but I just kind of dismissed it as "huh, odd". 🤦‍♂️

[Grum]

37 minutes ago, shad68 said:

Come to think of it... son of a... the head light is also powered through main fuse B, and I think that might not have been working either when I checked the other electrics (again not entirely sure), but I just kind of dismissed it as "huh, odd". 🤦‍♂️

 

You Are Correct -  If you also have a headlight issue then that is further strong evidence things might not be too good with Main Fuse B 30amp and its wiring.

 

Try this download link, hope it works. Its a fantastic colour wiring diagram for the 5gen. Makes following wires soooooo much easier, priceless for any 5gen owner!

5th Gen Super High Resolution Wiring Diagrams https://www.vfrdiscussion.com/index.php?/files/file/230-5th-gen-super-high-resolution-wiring-diagrams/

[shad68]

39 minutes ago, Grum said:

 

You Are Correct -  If you also have a headlight issue then that is further strong evidence things might not be too good with Main Fuse B 30amp and its wiring.

 

Try this download link, hope it works. Its a fantastic colour wiring diagram for the 5gen. Makes following wires soooooo much easier, priceless for any 5gen owner!

5th Gen Super High Resolution Wiring Diagrams https://www.vfrdiscussion.com/index.php?/files/file/230-5th-gen-super-high-resolution-wiring-diagrams/

I've been using that the whole time, fantastic resource indeed! Would've gone mad trying to trace things on the black and white diagram by now.

[shad68]

On 6/30/2023 at 12:03 AM, Grum said:

you MOST CERTAINLY are Not "a massive idiot"

You might want to take that back, because turns out it was just the main fuse B being fried all along 🙈 When I checked it, it was visually obviously fried and with a new one installed the bike started up and idled just fine. I haven't done a test ride yet because I hadn't had time to put the fairing etc. back together again, but I don't expect any trouble.

 

Big fail on my part, I didn't even think to check it because there was a fuse specifically for the fuel injection, ignition and pump circuit right there in the fuse box and surely the main fuse must be fine since the electrics aren't all dead! And when I looked at the wiring diagram I left myself get distracted by the complexity instead of just following the wiring all the way to a power source to see what failure points are inbetween.

 

So lesson learned, don't make any assumptions about things like fuses and always trace back to a power source in the wiring diagram before diving into the deep end of diagnosing and measuring stuff if there are electrical problems.

 

What really stings is that clumsy me managed to put a dent and some substantial scratches into the tank while I was trying to get to things to test them. And if I had just checked the main fuses right away that wouldn't have happened 🤦‍♂️

 

Anyway, a blown fuse might mean that there's still some undiagnosed underlying problem that caused it to blow in the first place and will burn the replacement eventually as well. But the way the fuse looks I think this might have been more of a case of the fuse failing from thermal stress rather than electric overload. Either way, I'll be carrying a set of spare fuses under the seat from now on.

[Grum]

Good find but you really need to replace the fuse holder and cut out the single wire inline connector, simply replacing the fuse will not solve the problem long term, otherwise it might end up like the picture previously posted.

 

You can purchase a good weatherproof inline 30amp fuse and wiring from any good automotive parts store, something like the item shown.

A product like Ox-Gard is good to smear onto the fuse legs.

 

Also check your charging voltage at the battery make sure you are seeing around 13.5 to 14.5v engine at idle and 5000rpm both cold and warm engine.

 

[vfrgiving]

22 minutes ago, Grum said:

Good find but you really need to replace the fuse holder and cut out the inline connector, otherwise it might end up like the picture previously posted. 

 

 

 

 

I was only in that area this morning with a butane torch, solder, and adhesive lined marine heat shrink doing a regulator connector bypass.  I could have taken care of that fuse holder and single contact plug at the same time but no.... 🤦‍♂️  Oh well, maybe later in the week.  At least I don't think I would need to pull tail plastic again.

[shad68]

On 7/1/2023 at 11:43 PM, Grum said:

Good find but you really need to replace the fuse holder and cut out the single wire inline connector, simply replacing the fuse will not solve the problem long term, otherwise it might end up like the picture previously posted.

 

I've got myself an inline fuse like that. How do you recommend installing it? Just cut off the old wiring below the plug and solder the old wires together with the fuse holder wires?

[Grum]

You want to remove the single wire inline connector as well as the fuse holder refer to the previous picture posted.

See if you can expose enough of the wiring so you can either solder and sleeve the joins to the original wiring or use high quality crimp inline joiners with added heatshrink sleeving over it. See attached.

If you're not confident then perhaps the job could be done by an auto electrician it wouldn't take him long.

[Lorne]

On 7/4/2023 at 7:15 AM, shad68 said:

Just cut off the old wiring below the plug and solder the old wires together

 

Crimping is the best option for electrical connections on motorcycles. This requires, of course, the proper crimping tool and crimps. They may cost more than bargain-priced items, but will be far more reliable. They don't solder in aviation or motorsports for this reason.

 

Crimping vs Soldering

[Grum]

Great article Lorne, completely agree with you. Thanks for that.

[shad68]

Thanks for the advice, I'll look into getting a crimping tool.

 

The fuse holder definitely doesn't look great inside, so I'll try to replace it sooner than later.

 

On 7/1/2023 at 11:43 PM, Grum said:

Also check your charging voltage at the battery make sure you are seeing around 13.5 to 14.5v engine at idle and 5000rpm both cold and warm engine.

 

Finally got around to that yesterday, battery voltage is at a really steady 14.5 V both at idle and 5000 rpm (held for 4-5 seconds), cold and warm (85-95 °C).