02 f4i Won't Start
#11
07-08-2015, 01:55 PM
Join Date: Apr 2015
Location: Massachusetts (Berkshires)
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#12
07-09-2015, 12:36 PM
Join Date: Apr 2015
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Last night I checked the wiring for the ignition coils and it was all going to the correct cylinders, so we can rule that out. I pulled the spark plugs from cylinders 1 and 2 and they were both pretty fouled as I would expect, given the gas mileage I was getting. The plugs smelled strongly of gasoline.
I checked the gap and they were correct at .85mm
I hooked up the ignition coil and spark plug from cylinder 1 to the wiring for each cylinder in turn and tried to see if I could get a spark when grounding the plug to the cylinder head and could not get a spark with any of them.
I checked the gap and they were correct at .85mm
I hooked up the ignition coil and spark plug from cylinder 1 to the wiring for each cylinder in turn and tried to see if I could get a spark when grounding the plug to the cylinder head and could not get a spark with any of them.
#13
07-14-2015, 12:38 PM
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Just wanted to check back in with an update.
Last night I checked all of the ignition coils' primary and secondary winding resistances to make sure they were all working ok and I was reading correct values. I checked for continuity from the ignition coil wiring back to the ECU and everything checked out as well.
Just for the hell of it, I also checked the fuel injectors out (resistance across injector pins, continuity to ground on wiring, and battery voltage on the hot side of the wiring) and everything was good.
I pulled the spark plugs from cylinders 3 and 4 (1 and 2 were already out) and they were badly fouled and smelled like fuel just like cylinders 1 and 2 when i removed those. I'm thinking that the cylinders must have been flooded. I left the spark plugs out of the cylinders over night to allow any fuel in the cylinders to evaporate and when I get home after work today I am going to put the new FPR back on the bike, clean up the spark plugs, charge the battery, and see if she'll start.
Keeping my fingers crossed.
Last night I checked all of the ignition coils' primary and secondary winding resistances to make sure they were all working ok and I was reading correct values. I checked for continuity from the ignition coil wiring back to the ECU and everything checked out as well.
Just for the hell of it, I also checked the fuel injectors out (resistance across injector pins, continuity to ground on wiring, and battery voltage on the hot side of the wiring) and everything was good.
I pulled the spark plugs from cylinders 3 and 4 (1 and 2 were already out) and they were badly fouled and smelled like fuel just like cylinders 1 and 2 when i removed those. I'm thinking that the cylinders must have been flooded. I left the spark plugs out of the cylinders over night to allow any fuel in the cylinders to evaporate and when I get home after work today I am going to put the new FPR back on the bike, clean up the spark plugs, charge the battery, and see if she'll start.
Keeping my fingers crossed.
#14
07-16-2015, 02:51 PM
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My bike is running again! Yesterday I bought some new cheapo spark plugs and installed them, then put the new FPR back on, reassembled everything and the bike started right up. Just for the hell of it, I tried the old ECU again to see if it'd run and it didn't, so at least I didn't buy an ECU when I didn't need to.
So here's what I think happened. Initially the ECU went bad, so when I replaced it it fixed my problems for a while. Around the same time, the FPR must have given out causing my terrible fuel mileage, flooding the cylinders, and fouling the spark plugs. It was just a coincidence that the bike stopped running after I replaced the FPR because the plugs had just become so fouled. So replacing the spark plugs and letting the cylinders air out was all that was needed to get the bike running again. And finally, replacing the FPR should prevent the plugs fouling and the cylinders from flooding in the future.
Having 2 unrelated part failures (ECU and FPR) so close together had me over-complicating the problem in my head, but I'm glad I finally got this sorted out. Thanks for all the help 74demon and Conrice; I really appreciate it.
So here's what I think happened. Initially the ECU went bad, so when I replaced it it fixed my problems for a while. Around the same time, the FPR must have given out causing my terrible fuel mileage, flooding the cylinders, and fouling the spark plugs. It was just a coincidence that the bike stopped running after I replaced the FPR because the plugs had just become so fouled. So replacing the spark plugs and letting the cylinders air out was all that was needed to get the bike running again. And finally, replacing the FPR should prevent the plugs fouling and the cylinders from flooding in the future.
Having 2 unrelated part failures (ECU and FPR) so close together had me over-complicating the problem in my head, but I'm glad I finally got this sorted out. Thanks for all the help 74demon and Conrice; I really appreciate it.
#15
05-21-2022, 04:04 PM
Hey guys, I could really use some help diagnosing why my 02 f4i won't start. I bought it last September, rode it a couple times and then had to put it away for the winter since I live in MA. A couple months ago when I first got my bike out of the garage to start the season, everything was going great. It would start right up and it seemed to be running relatively well. I rode it twice in a few days and then decided to do an oil/filter change (Rotella 5W/40 and K&N filter) and replace the air filter (washable K&N filter).
When I went to start it up for my next ride it was really struggling to start. It only started once I gave it some gas and if I let off the throttle the revs would drop and it would stall. After doing this a couple times, the engine wouldn't even fire, but it was still turning over.
I checked the FI codes and it was throwing 1, 2, 7, 8, and 9. I think that most of these were from the previous owner and had just never been cleared, but I checked out all the codes anyway. 7, 8, and 9 correspond to the ECT sensor, TP sensor, and IAT sensor respectively so I checked to make sure that the sensors were all plugged in correctly and were returning the appropriate resistances. Everything checked out. None of those sensors should have prevented the bike from starting though as the ECU would just simulate a preset value; correct me if I'm wrong.
So next I checked the MAP sensor for FI codes 1 and 2. It was plugged in correctly and the vacuum hose was connected; it was also returning the correct resistance according to the Haynes manual. I did notice a small tear in the vacuum hose near the connection to the MAP sensor so I used some Krazy glue to seal the hole and then tested to make sure that air could still flow through the tube. The bike still wouldn't start. Fuel pump primes, the engine turns over, but it won't fire.
Checked the kickstand sensor, clutch sensor, and engine kill switch and they were all functioning correctly.
Next, I checked the spark plugs and they were a bit fouled so I replaced them with some NGK Iridium plugs. Tested for a spark on cylinders 2 and 3 and I wasn't getting one. At this point I didn't know what else to check so I decided to buy a used ECU off ebay. When I got it, I swapped it out for mine and it started right up! FINALLY!
I thought at this point that I had finally solved my problem and I was ecstatic. Took the bike out for a few rides including one almost 70 miles and when I filled up the tank I calculated that I had only gotten 18mpg. Did some reading online and it looks like generally this points to a faulty fuel pressure regulator, so I ordered a new OEM one and swapped it out. Bike started up no problem afterwards and the exhaust was smelling a lot cleaner, no unburnt fuel smell. I didn't have time to go for a ride after I swapped out the FPR so I only had the bike running for maybe a minute.
The next day I went to take it out for a ride and the bike was struggling to start up again. Same symptoms as before. Gave it throttle and it would start, but only if I kept on the throttle. As soon as I let off it would die. At this point I checked the headers and noticed that only cylinders 1 and 4 were firing; 2 and 3 were significantly colder (could touch without getting burned). I decided to put the old FPR back on, just in case the new one was faulty and it still wouldn't fire. Now the bike won't start up at all. Fuel pump primes, engine turns over, but it won't fire.
Sorry for the novel, but I have no idea what to do next besides rip out the main wiring harness and check every connection. Any thoughts or suggestions would be hugely appreciated!
TLDR: Bike won't start. Replaced ECU, bike starts! Replaced FPR to improve gas mileage, bike no longer starts. Help.
When I went to start it up for my next ride it was really struggling to start. It only started once I gave it some gas and if I let off the throttle the revs would drop and it would stall. After doing this a couple times, the engine wouldn't even fire, but it was still turning over.
I checked the FI codes and it was throwing 1, 2, 7, 8, and 9. I think that most of these were from the previous owner and had just never been cleared, but I checked out all the codes anyway. 7, 8, and 9 correspond to the ECT sensor, TP sensor, and IAT sensor respectively so I checked to make sure that the sensors were all plugged in correctly and were returning the appropriate resistances. Everything checked out. None of those sensors should have prevented the bike from starting though as the ECU would just simulate a preset value; correct me if I'm wrong.
So next I checked the MAP sensor for FI codes 1 and 2. It was plugged in correctly and the vacuum hose was connected; it was also returning the correct resistance according to the Haynes manual. I did notice a small tear in the vacuum hose near the connection to the MAP sensor so I used some Krazy glue to seal the hole and then tested to make sure that air could still flow through the tube. The bike still wouldn't start. Fuel pump primes, the engine turns over, but it won't fire.
Checked the kickstand sensor, clutch sensor, and engine kill switch and they were all functioning correctly.
Next, I checked the spark plugs and they were a bit fouled so I replaced them with some NGK Iridium plugs. Tested for a spark on cylinders 2 and 3 and I wasn't getting one. At this point I didn't know what else to check so I decided to buy a used ECU off ebay. When I got it, I swapped it out for mine and it started right up! FINALLY!
I thought at this point that I had finally solved my problem and I was ecstatic. Took the bike out for a few rides including one almost 70 miles and when I filled up the tank I calculated that I had only gotten 18mpg. Did some reading online and it looks like generally this points to a faulty fuel pressure regulator, so I ordered a new OEM one and swapped it out. Bike started up no problem afterwards and the exhaust was smelling a lot cleaner, no unburnt fuel smell. I didn't have time to go for a ride after I swapped out the FPR so I only had the bike running for maybe a minute.
The next day I went to take it out for a ride and the bike was struggling to start up again. Same symptoms as before. Gave it throttle and it would start, but only if I kept on the throttle. As soon as I let off it would die. At this point I checked the headers and noticed that only cylinders 1 and 4 were firing; 2 and 3 were significantly colder (could touch without getting burned). I decided to put the old FPR back on, just in case the new one was faulty and it still wouldn't fire. Now the bike won't start up at all. Fuel pump primes, engine turns over, but it won't fire.
Sorry for the novel, but I have no idea what to do next besides rip out the main wiring harness and check every connection. Any thoughts or suggestions would be hugely appreciated!
TLDR: Bike won't start. Replaced ECU, bike starts! Replaced FPR to improve gas mileage, bike no longer starts. Help.
#16
05-21-2022, 04:06 PM
#17
05-21-2022, 04:07 PM
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