$100 907ie

discussions specific to the 907IE
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paso750
paso grand pooh-bah
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model: 750 Paso
year: 1987
Location: southern Germany

Re: $100 907ie

Post by paso750 »

If you lift the tank in front you'll see a rubber puck on which it sits. Don't know about the 907IE but on the P750 on the bottom/opposite side of it there's one of the main ground points.
twd46
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Joined: Sat Jul 24, 2021 3:08 pm
model: 907 I.E.
year: 1991
Location: USA

Re: $100 907ie

Post by twd46 »

Thanks. I actually spotted those ground points when I lifted the tank a few days ago. I just realized that I didnt answer your question from the previous reply.

The PO got the bike as part of a trade. He had no interest in the bike and had no knowledge of its past. I have managed to piece together some of its history by searching the vin. It was wrecked back in 2016 and came up for auction. I have no idea what happened to it since then. It has obviously been sitting for a while, but some things dont look as bad as others.
twd46
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model: 907 I.E.
year: 1991
Location: USA

Re: $100 907ie

Post by twd46 »

So I replaced all of the fuses in the fuse box and on the two fused relays. I cleaned all the connections I could find and still no start. However, I did disconnect the wire to the solenoid and it gets 8V which is exactly what I was getting at the plug going to the fuel pump at the bottom of the tank. What would cause it to be 8V instead of 12V? Also, I noticed that when I hit the starter button, the battery light on the dash blinks, so something is happening when I hit the starter switch. Is there some way to confirm that the starter solenoid is bad? Thanks. I think I am getting closer.

I also tried to bypass the starter solenoid but to no avail. I really thought that might work.
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paso750
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Re: $100 907ie

Post by paso750 »

Again, have a look at the wiring diagram. The two fused relays and the starter solenoid are connected directly to the battery. Their switching voltage comes from one of the two 15A fuses in the fuse holder. Follow its brown/black wire and you'll see that the current passes the ignition switch which connects to the bigger fuse (blue wire) and then to the battery. Measure the voltage of the battery, then at the 25A fuse and at last at one of the two 15A fuses. If there's the 4V voltage drop between both it's caused by the ignition switch. That's a very common problem on the other Paso models.
As for the starter solenoid. Disconnect the cable to the starter and connect your voltmeter instead. Then get a wire and connect the battery directly the solenoids switching input hence the one the start button/yellow-red wire connects to. 8V may not be enough to switch it therefore create a direct connection to the battery. (It doesn't matter if you remove the yellow-red wire or not). The relay should click and you should read 12V. If you read nothing it's not good anymore.
If it switches the 12V through, the starter (when connected back to the solenoid) should normally turn over the engine. If it doesn't remove the spark plugs and try again or better put the bike on the center stand and in gear, turn the wheel by hand and see if the engine actually turns over.
If the engine is free and the solenoid it tested ok the last thing I would do (mainly out of curiosity) is measure the voltage output of the starter solenoid towards the starter motor when hitting the starter button. Just to see if the voltage remains stable or is pulled down. The result actually doesn't matter. If the starter doesn't turn if full voltage is applied it's defective.
You obviously have more than one (electrical) problem.
twd46
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model: 907 I.E.
year: 1991
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Re: $100 907ie

Post by twd46 »

Thanks for the reply. I will perform those tests tomorrow. I know that the engine turns over because I just changed the belts a few days ago and I turned the rear wheel multiple times with no issues. Hopefully after tomorrow, I can more precisely pinpoint the issue.
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paso750
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Re: $100 907ie

Post by paso750 »

I turned the rear wheel multiple times with no issues
it was in gear as you did that? I'm sure it was but I have to ask ;) :truck:
twd46
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Re: $100 907ie

Post by twd46 »

Haha. Yes
nickta
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year: 1992
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Re: $100 907ie

Post by nickta »

twd46 wrote:So I replaced all of the fuses in the fuse box and on the two fused relays. I cleaned all the connections I could find and still no start. However, I did disconnect the wire to the solenoid and it gets 8V which is exactly what I was getting at the plug going to the fuel pump at the bottom of the tank. What would cause it to be 8V instead of 12V? Also, I noticed that when I hit the starter button, the battery light on the dash blinks, so something is happening when I hit the starter switch. Is there some way to confirm that the starter solenoid is bad? Thanks. I think I am getting closer.

I also tried to bypass the starter solenoid but to no avail. I really thought that might work.
Hi.
Check your battery voltage direct and see what is happening there.

Many a time a "good" battery isn't, well, that good.... It could be loaded down somewhere and only supply 8v to the bike. If it is, you can start disconnecting things on plugs (dashboard, lights etc). If you have luck and a lot of patience, you might find what is loading down the battery.

If something is loading down the battery, it will get real hot real quick!

Cheers.
Nick.
twd46
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year: 1991
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Re: $100 907ie

Post by twd46 »

Thanks Nick. Thats a good suggestion. The battery checks out since I use it for my 998 and I went for a ride this morning with no issues. I assume its good enough to start the 907.
twd46
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model: 907 I.E.
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Re: $100 907ie

Post by twd46 »

It turns over!!! But still no start.

I decided to try to bypass the starter solenoid one more time, and I heard the starter run. Then I connected the solenoid wires to the starter, connected the battery, and voila, the damn thing turned over! I suppose the starter solenoid didn't have quite a good enough connection or something.

Now, the fuel pump still doesn't prime. I assume the next step is to connect 12V directly to the fuel pump. Is this correct? If so, what is the best way to do so?
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paso750
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Re: $100 907ie

Post by paso750 »

Good, so the starter is ok. The issue remains the 8 volts. So measure the voltage at the fuses in the fuse holder!
There's no need to put 12V on the fuel pump directly. The fused relay will do just that once it gets the voltage it needs to switch. And of course if it's ok.
If you would connect 12V directly you'd only see if the fuel pump works. The bike wouldn't start as you'd have no spark.
twd46
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Re: $100 907ie

Post by twd46 »

Ok, which fuse is for the fuel pump? For some reason, I have been unable to find which one it is. Thanks again for your help. I feel like Im really close now!
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paso750
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Re: $100 907ie

Post by paso750 »

I could tell you or you could find out yourself if you finally had a look at the wiring plan. ;) However which one it is isn't important. There are three in the fuse holder. A 25A and two 15A. The two smaller ones are connected so you'll measure the same voltage. What do you measure on the big and what on the small fuses? (ignition on) It should be the same. I'm certain it won't be.
twd46
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Re: $100 907ie

Post by twd46 »

I have looked at the wiring plan on several occasions as it is found in the workshop manual. All it says (if I am looking in the right place) is "25 amp and 15 amp fuses." Perhaps I am looking in the wrong place.
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paso750
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Re: $100 907ie

Post by paso750 »

Not sure what more info you're looking for. Get a volt/multi-meter and measure the voltage on those fuses. Just do it! :lol:

Here's a picture of the ignition wiring only.
Starting at the ignition switch (10). The blue wire connects to the 25A fuse and that directly to the battery. The ignition switch switches the 12V through (Bn/Bk wire) to the two 15A fuses. From there the 12V get to the kill-switch and via the grey wire to one of the fused relays. So switching on the ignition activates relay 1 which wakes up the ECU which then activates relay 2 which forwards the 12V to the coils and (what is missing in this pic) the fuel pump. Before you do anything else or try identifying the relays make sure that there is full battery voltage on every fuse in the fuse holder. That is crucial for everything following. Checking the relays is only the next step.
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