2003 400 FSE Fuel Injection Issues

Headhunter99

Headhunter99

New member
Hi all,
Boy have I got a story for you. I bought this 2003 400 FSE end of last year and got to ride it all of 3 months before it gave out on me. It's got that common problem of the Fuel pump not priming when the ignition is turned on. Plus the fuel pump does not turn on after the starter has spooled and stopped. So I've changed everything in the system I could get parts for. I've also scoured this forum for any other similar occurance and tried all those fixes, ignition swtch, kill switch, etc.

First were the fuses and the relay. $11

So, yes, I jumpered over where the relay would be, and the fuel pump runs and pumps fuel. That of course was after I bought a new OEM fuel pump from Gofasters... $950

I've checked the original relay that was in there and the replacement relay I got by putting direct power through and both actuate.

I figured since the fuel pump relay actuation is an ECU function "maybe the ECU was fried" so new Magneti Marelli 15P $450... No change.

Since I can't find ANYWHERE a wiring diagram for the 2003 400 FSE, I've been going off of the 450 FSE for at least reference. If anybody has a link or reference to a way I can get a wiring diagram I'd be very grateful.

Having gotten fed up with not having any luck with physically changing parts to get it working and all of the wiring seeming to be in good working order (no opens or shorts where there shouldn't be) I looked for dealership support, and was told by both (relatively) local dealers that they "don't work on that" one because it was a four-stroke, and the other because it's fuel injected.

Total so far $1411 - Bought the bike for $3000
Now I found the Biketech OBD tool online for $1250, but before I jump to buying that I was going to put the call out to all my fellow Gas Gas enthusists to find out if there is a dealer or other shop in Washington or Oregon that has a diagnostic tool I can plug into to see if there's any codes I can clear and turn this boat anchor back into a motorcycle. I'm in Western Washington, But i'm willing to take a road trip if I have to.

I love it when it runs, best bike I've had yet. But does me no good if it wont start.

Thanks
 
I would suspect the wiring...can you recall the symptoms when it quit?

Does anything else light up when you turn on the ignition switch?

The ECU has a permanent live on pin 17 via a fuse, the ignition switch just signals the ecu to start but it powers lights and stuff as well.

Forget the diagnostic kit for the time being, it will probably only tell you what you already know!

If your ecu is live on pin 17 and with the ignition switch on it supplies 12v on ecu pin 26 you need to check that ecu pin 19 goes low. This is the fuel pump relay trigger and grounds the relay coil. There is a blocking diode between that pin and the relay. The position of that diode is not certain. Mine is on the back of the relay socket but it could be taped in the harness somewhere between the relay and the ecu (nightmare). The 12v supply to the relay coil is off the ignition switch.

Hope that helps
 
So I checked those wires. Verified I'm getting Voltage to Pin 26 When Ignition is switched on, then getting no voltage when switched off. Verified Pin 17 has permanent 12V. Diode was oriented correctly. Removed Diode (located in the fuse box and soldered into a Buss fuse adapter) to check for back voltage from pin 19. None. switching off and on I get a constant 4 Ohms of resistance. there is no change in readings. With the diode in I get constant voltage across the diode heading to pin 19 whether the ignition is switched on or off. It seems as though the relay actuation circuitry is not grounding, but I'm not sure what to do now, I've already tried a different ECU and cleaned all the ground connections I could locate.
 
There should not be any voltage on pin 19, using an ohm-meter to measure on live electronics is sure to get irratic results. Can you get the fuel pump relay to pull if you ground the cable to pin 19? (migth wanna disconnect it from the ecu first.

I have attached a different schematic, an older version. Might do you some good.
 

Attachments

Maybe i'm to simple for this, but you jumpered across where the relay goes and it pumps up like it should ? And yet you dont think its the relay ?
 
bergerhag said:
There should not be any voltage on pin 19, using an ohm-meter to measure on live electronics is sure to get irratic results. Can you get the fuel pump relay to pull if you ground the cable to pin 19? (migth wanna disconnect it from the ecu first.

I have attached a different schematic, an older version. Might do you some good.
Click to expand...

Perhaps I didn't make it clear.....pin 19 ecu is the switching line for the fuel pump relay. If the fuel pump relay is on (closed) there will be no voltage at that pin. When the pump cycles off after 2 or so seconds of no engine rotation that line will rise to battery volts less the coil and diode voltage drops. As soon as the crank pulser detects movement the ecu grounds that line turning on the relay. As Nick said you might want check the relay and its connections first to make sure the relay is ok. If pin 19 doesn't ever ground the relay then it could be one of the inputs or outputs from the ecu that are the problem. The ecu tests all the sensors, the coil and the injector before it will ground that pin 19. There are from memory 3 failures that will prevent the ecu from allowing the engine to start and therefore will not ground the pump relay pin. There may be more. They are a shorted or open coil, a shorted or open injector and an input from the tps which is outside the normal operating limits. The water, air and pressure sensors are also checked but if they have faults the ecu will run with a set of defaults and allow starting to be attempted.
Hope that helps

BTW bergerhag the diagram is almost the same as the later ones except for the led I believe
 
Headhunter99 said:
-snip-
Now I found the Biketech OBD tool online for $1250, but before I jump to buying that I was going to put the call out to all my fellow Gas Gas enthusists to find out if there is a dealer or other shop in Washington or Oregon that has a diagnostic tool I can plug into to see if there's any codes I can clear and turn this boat anchor back into a motorcycle. I'm in Western Washington, But i'm willing to take a road trip if I have to.

I love it when it runs, best bike I've had yet. But does me no good if it wont start.

Thanks
Click to expand...

The Magnetti Marelli Motorbike Diagnostic Program that is used by Gas Gas is also used (or was, in 2004) by Harley Davidson, Triumph, and Moto Guzzi (and maybe Ducatti). Just plug in the interface cable to the plug under the seat, near the battery. The user will have to first set the program to work for the "15P" ECU; and then it will diagnose the complete engine management system.

The dealer cost on that system was around $400 at the time, so I don't think it would be nearly as expensive as the program you mentioned. You may be able to get a semi-local dealership to put your bike on their diagnostic program for a nominal fee.

One more thought. One time, I couldn't figure out why the fuel pump on my 2003 FSE400 wasn't kicking on when I turned on the key. The most I could get was a "fast clicking" from the fuel pump relay. After waiting for and installing new fuel pump relays, I figured out that my battery was too weak to work the fuel pump. After a new battery, it ran fine, even after I reinstalled the old relays.

Good Luck with your problem.
Jim
 
Last edited:
If you are tech savvy this will do most of the commands for the 15p and m variants and it comes with source code so it can be modded to fully support them. It also has support for the quirky 'K line' interface that our model uses.
http://sourceforge.net/projects/iaw-scan/
You will need to construct or buy the interface ($20 worth of components) to get it working but it may be worth a try if you are so inclined. Also it should be possible to contact the author and have him add the relevant commands/error code interpretation for the bike versions
 
hi, if you have a kill switch/button that rubber key goes into on the 400 just unplug the wires 2 wires that go to it this by passes the system or at least it does on my 450. one less thing to worry about in the wiring just primes up with ignition turned on.
 
It's running again

Thanks again for all your advice on this, but It's running again. I decided to just throw all the original equipment back in, including relay and ECU, and it fired right up. Don't ask me why, but I think it might have just been moisture in the ECU. After letting it sit in a cool dry space, case open, for about 3 months.
 
Hi Headhunter99

I've had the same issue on my 2004 fse 400 & after checking all the electrical connections I found a relay in the airbox compartment with severe corrosion on the contacts. After cleaning this its been fine I also managed to source one for ?6 on ebay (from a fiat punto of all things)
 
gasgasjimmy15 said:
Hi Headhunter99

I've had the same issue on my 2004 fse 400 & after checking all the electrical connections I found a relay in the airbox compartment with severe corrosion on the contacts. After cleaning this its been fine I also managed to source one for ?6 on ebay (from a fiat punto of all things)
Click to expand...

Unfortunately I have spoken too soon as after an hours ride the fault returned whilst riding up a steep hill, total loss of power & then unable to start / tickover. Can anyone help????
 
Any one out thier no were to get quick release fuel couplers for gasgas fse400 2002 both ends one on fuel lines and the other one for top of tank x2 of them thanks johnmc
 
Johnmcm said:
Any one out thier no were to get quick release fuel couplers for gasgas fse400 2002 both ends one on fuel lines and the other one for top of tank x2 of them thanks johnmc
Click to expand...

In the US, I would call one of the more aggressively advertising GasGas parts dealers, such as Matto Cycles, or one of the longer term GasGas dealers that traditionally stocked a lot of parts, such as Halls Cycles.
If you can't get any good information from the above suggestioed sources, the former importer of GasGas motorcycles and parts, https://cpd.direct/ , might be able to assist you in your quest.
 
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