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08 sportster problem

6

67hat34c

Active Member
Update and recap of problem:

Bike has always run fine. Problem was with low fuel light.
Warranty was getting ready to run in March 2010 so i took it to have this repaired under warranty and here starts the problem.

March- replaced fuel pump module and this took car of fuel light. However notice bike was running lien so I took it back under warranty.
THey confirmed lien and said it was due to the stage one download so they recommended race tuner and I agreed. They did have to dissassemble top end to confirm no damage due to lien running and all ck out ok. They tuned with race tuner. I picked it up and notice that it hesistated once in a while, I brought it back and they retuned it. Still noticed hesitation so they tuned it a 3rd time. Then hesitation became worse so they replaced injectors and no change, then map sensor and no change then crank position sensor and no change.

They have never been able to reproduce the symptoms but are taking my word for it.--another story in itself.

Problem is intermittent it will hesitate slightly on accelerating and struggle slightly here and there while riding. If you sit at traffic light for over 60 seconds and then accelerate at normal pace it will sometimes stumble very hard. When it is cold it is more consistent and less random. At 125 degrees I can get it to stumble everytime I stop and waite for 60 to 70 seconds. After 150 degrees it will become more random and only do it slightly. (cant figure why shop hasnt been able to replicate though)

I believe it to be a problem with fuel pump module since that was a new part and it never ran bad prior to this but it could be an ECU issue also. Shop says however that fuel pressure is ok. Shop has it again and I gave mechanic explicit instructions how to replicate problem. Either way he is replacing the fuel pump assembly and I will pu again tonight.

Here is my question, if it is not fuel pump then could there be an issue with the ECU from the Super Tuner? Or could there be some issue with the voltage to coil? Some other electrical issue since some of this had to be taken apart when they pulled top end?

By the way I checked all fuses, ground and electrical connections and all were fine. I also put a spark tester and verified equivilent volts to each spark plug. Plugs are burning the same as well and plugs were new in march, bought from HD.
 
If your wondering if it is from the top end, I would do a compression test/cylinder leakage test. That would tell you with 95% assurance your OK there. If they tell you they did test that, ask what the numbers were. Remember the SEST is just software that is driving the ECM. Therefore it is Highly remote (0.2% chance) it is the ECM itself. I would also reassure myself that the fuel pump pressure was really ~60psi.

Question: You are logging no DTC's? None at all? Is this the ONLY issue you are having with bike.
If you were to snap WOT in 4th gear from a 2200 RPM roll, and take that 1 gear all the way to red-line, does the bike perform ok without a hitch?

The 125 & 150 degrees you are quoting,, is that oil temp?
Do you have & own your VCI?
 
Being it acts differently at different temps, have them check the cylinder head temp sensor on the rear of the front cylinder for it's values.
 
You can power through it when it is hesitating. If you run her hard and wind it up it is fine. All problems seem to be at lower rpm's. I also believe fuel efficiency is down.

Fuel pump pressure regulator problems and or fuel leaking within the unit tend to cause the symptoms I am seeing, at least that is all I could find with my research.

Re checking engine compression would be a good idea. I tried it the other day but the plugs in the harley are even smaller than the chevy so my fitting would not thread in.

My diagnosis is based on fact that it ran fine unitl they replaced fuel pump and tuned with super tuner coupled with head removal and disassembly of the top end. Purchased bike new at this dealer and had about 15k on it when they replaced fuel pump assembly to cure the low fuel light issue. so for first 15k she ran great with stage 1 kit and v&h slipons.

I only found it was running lean when I picked it up after fuel pump change. i notice inside of pipes was light gray instead of black. Didnt say anything and put 500m on it and noted pipes still not turning black so i pulled plugs and found them caked with white residue. Mechanic at hd said burning oil and too lien. They did compression and leakdown then pulled heads to inspect and found no issues. Stated the caked on stuff may have been fuel instead of oil. have put 2k on it since and new plugs do not have any residue on them so they were likely right.

One thing I can add is that it seems like when you pull plug wire while it is running that front cyl makes big difference but rear one does not make as much of a change. Both plugs look the same and length of spark is pretty close, front slightly longer than rear, used the basic coil output guage that measures length of the arc. I also reached up and felt around coil and no shock, no arcing around plugs either.

The tech at this shop is their most experienced, 20yrs with bikes and another 15 with cars before that. He is the shop foreman etc. Is there stuff he doesnt know... well of course. I even proved him wrong on the low fuel light issue, another problem he could never reproduce until I showed him how. (this is why they are taking my word for it regarding current issue and also a long story)
 
Glider the temp sensor is on rear cyl on the sportster. This is something I also considered, they would have had to remove this sensor when they did top end so it still could be an issue but I am banking on fuel pump assembley. Though the map sensor was also a good guess since it is dual sensor and measures ambient temp but it was ruled out.

Well it is very frustrating and I believe the solution is near. I wanted to post this not only to get other ideas but also to give other sportster owners info in the event they have a similar issue.
 
Mechanic is wrong, white is not burning oil, it would be black and wet looking.

I feel it is a fuel delivery problem but a low fuel pressure would show more at the upper speeds where fuel demand is higher. Just because the pump is new??? It doesn't mean it's good and a fuel pressure test would bear this out.

I would verify the compression based on what you say about the rear cylinder not making as much of a change from pulling the wire.
 
Since you can power through the problem area, I would say the ignition is not the problem. It is funny that the fuel supply does keep up with the engine under heavy demand during high RPM pulls.. Indicates vacuum leak.

Get the 12mm adapter for your compression gauge.

If the fuel maps are the same as when the bike was running good, it can be a vacuum leak. That will show up big time at idle and it won't have that big of an effect at WOT.

Perform a propane leak check. Since they had the top end off, you never know.

No reply to:
DTC codes.
Have you ever seen any during the course of this problem.
 
From what I read about sportster fuel pump, the problems were with pressure regulator and they were notorious for slow speed problems.

THey did the vacuum leak test but I may have to do this myself.

Not same map, Had stage on download and ran fine. But developed what appears to be lean running so they recommended super tuner. Super tuner was added after i put a few hundred miles on the new fuel pump. Those were highway miles to and from Daytona during bike week.

I thought they were full of it when they said the stage one can cause issues after the miles I had, 15k or so. They claim HD tech line told them that they have seen the stage one download cause trouble after bike has some miles on it. Cant figure out why miles would have a thing to do with it. If nothing has changed then why would it suddenly run too lien. Well I did not want to fight with them so I did super tuner, they comped me the price I paid for the stage one and gave discount on tuner. I figured it would be better than ever,,,,,,,,,well I was wrong. Lots of bikes get super tuner and I cant find anyone with these issues. These guys tune thousands of bikes so I cant imagine that it is the tune causing the problem.

Glider in my experience burning oil does just what you say, black goo on the plugs. Not clear why they said burning oil, and I will review the service book that shows plugs and diagnosis but i think the book also agrees with the first tech. I have the plugs still and may take photo of them and post it.
 
no ck engine light, does throw code think po 152 po 132, somtimes one or both these are showing one or both cyl running too rich but dyno sheet shows ok. I reset it and can ride for a while and it will act up like crazy and not throw it . Will ck later on and it will show up. Tech said if it doesnt show ck engine light then it is not an issue. It is within tollerance. i also checked several used sportsters on the lot with the similar mods and most show the same codes so I tend to believe them on this.
 
If you did not have the problem untill they installed the super tuner and dyno tune the bike, that throws a red flag up for me, the sensors giving a too rich code also throws another flag up. The dealer can do a simple fuel pressure test to tell if the fuel pump is working good or not, my bet is if you installed the stage 1 can map off the super tuner it would run great for you. Sounds like the tech has the experience but everybody screws up once & awhile, I speak from experience, and there is also the dyno factor, don't know what model dyno they have but a lot of them need filters cleaned & replaced to get good 02 readings and MAINTENANCE can be a factor, I speak from my own experience getting false readings. The reason for test rides after dyno tuning is because the michine is not always right, the seat of your pants is. Tuners also have their own opinons, whats rich to one might be lean to another, also some bikes are happier richer or leaner then others and the fuel map they are printing out might not be at the throttle position, manifold pressure or temp that you are having the problem at, the fuel map has a whole lot of cells in it and it don't take many bad ones to mess with a bike performance. Good luck with this issue but it should be simple as a couple of tests.
 
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