Discussion in '5th Generation 1998-2001' started by gips, Oct 21, 2019.
I still suggest trying to prime several times before cranking.
This was tested of course, also in previous posts i mentioned that fuel pump is already tested and is working fine. It holds steady pressure, also bike is not having any problem other than the cold start. If i start the bike in the morning and shut it like in 1min, i can easily start it first time for example 4 hours later. The problem is very specific, when bike sits on the cold overnight. And it looks like i am not the only one He did start it at a lot colder temperature tho, but i am positive mine will have the same problems at this temperature. Not that having lights on, at this temperature helped the battery
OK than perhaps next I'd try cranking the bike with the fuel disabled and then see if it starts quick. Hotwiring the starter or pulling a fuse or relay to cut fuel injection (not just the fuel pump). This will warm the heads I suppose but also build oil pressure, maybe if you have scuffed bores or something you have poor cold compression.
If it smells of fuel when cranking with the fuel injection disabled that'd also be a good clue.
I have a question regarding the fuel filter on this bike. Does anyone know the size of the hoses that connect to it, are tehy 6mm or 8mm. I am looking to replace it, as i will be cleaning the tank anyway. Unfortunately i don't want to buy a honda one. 50 euros for a simple paper filter ..... thanks, but no thanks. So i am aiming for universal filter and wondering about the size of the hoses.
Some news on this issue. Yesterday I decided to spray some ether in the intake and see , if it makes any difference. Well, the bike started 1st time and kept good rpm, so the problem is obviously not enough fuel during cranking and afterstart. Fuel pump is fine, fuel filter was changed and the tank cleaned. ECT sensor is giving good resistance.
Must be fuel injectors ?
Again I'll suggest disabling the fuel injection and just cranking the motor for 15-20 seconds, then seeing if it'll start normally. Hotwiring the starter would be my suggestion, key completely off. Then if it starts right up you might have learned if your issue is addressed by the oil pressure coming up, maybe compression. If this procedure has no effect that points to FI. Ether helps but it might crutch a low cold compression problem.
This write up sure makes it sound like the problem is fuel-delivery related (which in the fuel injection world means "fuel pressure related"). When you say "the fuel pump is fine" are you saying it has been tested on a test rig with a pressure gauge?
It should very quickly build pressure to somewhere like 50 psi or even more if the pump is good.
You've closely inspected the fuel pump wiring? No corrosion in the connector or chafing on any of the related wiring as it traces back into the main wiring harness wrapping? Both inside the tank and out.
Ok made the check with thinning the oil by cranking, but it didn't make huge difference, so its not compression related. Pump does over 5bar of pressure tested it with an adjustable fuel regulator. Im thinkin of injectors too, but have no way to test them. Have to bring them somewhere, but this will happen in several weeks as i have 3 cars to take care of firat.
Isn't one of the most common issues with the 5th gen the FPR? If you spray fuel into the intake then I'd suggest its too lean for a COLD START. I'd also look into pulling the injectors to get them professionally cleaned - 20 years is a long time especially when the bike hasn't been ridden much.
Mine is having similar symptoms as OP, I'm curious to see what the outcome ends up.
Maybe some Chevron fuel system cleaner in the tank and a nice long run through?
If you crank it just short of starting and immediately pull a plug, is it wet and smell like gas?
I'm not sure if injectors can be lazy and not lift open for the first few attempts and then work normally. Maybe if current was low they'd be intermittent during cranking but work OK once the alternator was doing it's job.
With that in mind, maybe try boosting the battery for a cold start and see if it responds normally? What is the battery voltage, before and after the first starting attempt, but before the second?
I agree with the idea of checking to see if the bike starts better with a really solid 12 volt supply (that has a lot of cold-cranking amps available).
You should connect up to a car battery to see if it changes the start. BUT MAKE SURR THE CAR'S ENGINE IS NOT RUNNING WHEN YOU DO THIS. Just the battery.
The reason I'm interested in this experiment is that I don't know whether the Honda PGM-FI system does any compensation for lower-than-normal voltage during cranking. If your bike's electrical system is dropping below 12 volts during cranking the engine will experience both reduced spark plug performance and reduced fuel injector performance.
If your battery is a bit weak the car battery will insure that the bike's system gets a solid 12 volts while you crank the engine.
I think it doesn't get concerned until about below 10.6v...
The ECU might run fine at a lower voltage but the physics of lifting an injector pintle against the fuel pressure with less energy might matter.
Could be indeed. That is one thing i haven't fully tested, because when i fixed the line the vibration at high vacuum was gone, so i decided it works, but in fact it could have gotten better, because i plugged a vacuum leak . Strangely the bike started absolutely the same with the hose with hole in it........could be, if its indeed shot. It should have been worse before and better now, but strangely there was no difference.I will test it upcoming days, i can easily test it without removing it. I have a wideband sensor, i will plug it in and start the bike, then i will remove the hose from regulator and plug it and check the AFR , if it changes this means regulator works, if it does not, or too little..... regulator is shot.I will also try with a car battery to see, if this makes any difference.
Yep - thats about the 10.6v - any lower than that and the injectors just won't fire..
Did you get this figured out?
In my instance I just resolved - I re-checked the connection to the battery terminals and moved the battery tender connection from under the motorcycle connectors to on top (which is how I should have done it to begin with), I then cleaned connections and tightened the bolts with a screwdriver followed by a socket just another 1/8 turn or so.
No more issues starting since in even colder weather than earlier.
I had previously measured battery voltage (off) - it was great and in fairly new condition and couldn't imagine the battery had anything to do with it so I didn't do those steps earlier.
Good catch, that.
Not an easy thing to figure out, the fact that while your battery might be in tip-top condition, it could be true that due to its connections to the bike's wiring harness it is unable to provide normal starting amperage.
I've seen similar situations over the years. The most profound was an AT-6 Texan racing plane (Reno Air Races) that had the battery re-located way to the rear of airplane for weight distribution reasons. In the work to relocate the battery further aft the decision was made to use an aluminum battery cable (another weight saving choice). It turned out that the combination of this new aluminum battery cable plus its longer-than-normal length was causing an overall voltage drop to the point that the aircraft was very hard to start.
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