Fuel relay switch and charging system

[PaulE]

I have a 1990 FJ1200 CV3 California model that suddenly would not start.  When I turn on the key the fuel pump does not kick in. I checked the pump and it works fine off the bike. I thought it was the fuel pump relay switch that went bad. I used a multi-meter to check resistance at each of the six blades on the relay and got no reading from any of them.  According to what I could find on the internet my fuel pump relay switch should have 10 or so blades but mine has only six.  It looks like the relay from an '86-'87 FJ1200. So I bypassed the fuel pump and used gravity feed to get fuel to the carbs.  That part works fine.  It gets plenty of gas without the pump. It runs fine except that after riding for 10 minutes or so the battery is not strong enough to restart the bike. I put the multi-meter on the battery and with the engine running can get a reading of 14.2 volts DC.  When you rev the bike the battery goes from 12.6 volts up to 14.2.  If you don't rev the bike and just let it idle it slowly drops voltage down to around 11.7 and stabilizes there.  The charging system seems to work and is strong.  My question is: is the fuel pump relay switch (which I think is defective) a part of the charging system?  Could it somehow be draining the bike at a faster rate than the charging system can charge it? The charging system is working (over 14 volts at higher rpm) yet the bike's battery is not charged enough to restart the bike after a 15 minute ride.  Maybe, just coincidentally, it's time to replace the battery.  I will take it to have the battery checked. I have a Clymer's shop manual but it does not tell how to test a fuel pump relay switch.  Anyone have any ideas how to test the relay switch?  It is my 3rd FJ and I love these bikes.  Would like to get it back on the road.  Thanks in advance for your help.

[CutterBill]

The bike will not start? Or will not crank?

No, the fuel pump relay is not part of the charging system.

Entirely possible that the battery is not holding a charge. Put battery on a trickle-charger overnight. Report back here with results.  Note: your charging voltage is low at idle but a bad battery can make the voltage regulator do strange things.

Check the infamous red connector in the wires from the generator. Disconnect and check for corrosion and overheating.

[PaulE]

The bike cranks over and starts.  It is just after I have ridden it for 15 minutes or so that it won't restart. I have trickled charged it a couple of times with the same results.  I am going to have the battery checked.  I usually scratch in the month and year I replace  it so maybe this is the original battery from when I bought it 3 years ago. That would be quite the coincidence for it to go out the exact moment the relay switch went out too.  But, it could happen.  I will look at the wiring as you suggest.  Thanks.

[CutterBill]

"The bike cranks over and starts...."
Got it. 

"It is just after I have ridden it for 15 minutes or so that it won't restart."
Does not crank? Or cranks but does not start?

If it will not crank, then it is a battery/charging related issue.
If it cranks but will not start, the battery is fine.

And 3 years is a long time for a bike battery.

[CutterBill]

Also...

The fuel pump relay (for all FJ's with a pump) has only 6 wires.  Your internet source that shows 10 wires is wrong. Your relay can't look like the 1986-87 relay because fuel pumps were not installed until the 1988 model.  Testing the relay with an VOM will not work because that is a solid-state relay.  The relay provides several functions: while starting, the pump will run for only 5 seconds. If the engine hasn't started by then, the relay shuts off the pump. This can drive you crazy while troubleshooting. Also, if the engine stops running (ignition stops) the relay will shut off the pump. 

Too bad that you don't have the FSM; it goes into great detail on exactly how to troubleshoot the fuel pump system.

[TexasDave]

My reply copied from  FJ running problems.
I have a Clymer Manuel for the 84-93 models and it goes into great detail in diagnosing this problem in the fuel pump section. Testing voltage from the wiring harness disconnected from the fuel pump relay to see if you are getting good voltage from the igniter to the relay. The relay is powered from the igniter. It also tests the relay with it plugged in to see if the voltage is good and the relay is good. Unfortunately it could be either the igniter or the relay OR a bad connection between the two. Also this is a six pin relay. This also looks to be a two person job as one has to watch the voltmeter. Sorry I can't be more help.

My reply to Cutter Bill
You can test the fuel relay with a VOM as per the Clymer and factory manuals. With the relay hooked up you can test the output voltage from the relay to the fuel pump. But like you said it has to be done within 5 seconds--hence a two man job. However the relay is powered from the igniter so the relay could be good just not getting voltage from the igniter so that must be tested also. The Clymer manual also diagnoses this problem in great detail.

Dave



 

[CutterBill]

.... I used a multi-meter to check resistance at each of the six blades on the relay...

You said you were checking resistance, not voltage.  Words matter...

[PaulE]

Thanks for the response. Sorry I did not get back earlier, we have company this week and I am fitting this in in between playing tour guide. I received a new (to me) fuel pump relay switch from ebay today. Tomorrow I will have the battery checked out and see where it goes from there. The bike will crank after the 15 minute ride but just barely. I think that if it cranked over normally it would fire right up.  The problem seems to be the battery.  As soon as I can get to the battery shop and get it checked or buy a new one I can go forward.  I checked the resistance of the fuel pump switch relay with it off the bike so there was no voltage to the switch. Thanks again for your info. Will keep you posted. 

[PaulE]

Well, after replacing the fuel pump and the fuel pump relay switch with parts from e-bay it is back on the road.  The battery was fine.  It was good to learn that I can by-pass the fuel pump entirely if it goes out in the middle of nowhere by inserting a piece of 1/4 inch tubing (which I now carry on the bike) between the intake and out flow fuel lines to the pump and use gravity to get home again.  Thank you gentlemen for helping to solve the problem with your knowledge and expertise.  It was greatly appreciated.

[TexasDave]

Glad you got it fixed and are back on the road.

Ride safe
Dave