QuestionHi Christopher - I have a issue I am praying you know the answer to. I have a 1983 Honda Magna 750 V45. It had sat for about three years in a garage. Carbs were rebuilt, frozen front brakes were fixed, gas tank was cleaned out, clutch cylinders were cleaned up, etc.
We are having trouble getting fuel to it - the fuel pump was replaced, the fuel relay was replaced, the in-line filter was replaced. The manual says to take the fuel input off the carb and put it in a glass. Turn the ignition on (but dont start) and see how much fuel comes out in 5 seconds. None comes out. It says several ounces should come out. When we push the starter, fuel pumps out into the cup in seemingly good amounts. Do you think the manual is correct, that fuel should come out when just turning the ignition on?
As you sit on the motorcycle, the fuel enters the carbs on the left hand side of the motorcycle and feeds the other three carbs via plastic pipes that connect the carbs, just like the 84 that you have. The microfiche for my 83 suggests the fuel line Ts and feeds that carbs from both sides of the bike. When I got the bike and took out the carbs, there is no T in the fuel line and it only enters the carbs in one spot, the left side. Do you know if this is correct? Also, the fiche card shows a total of four plastic fuel pipes between the carbs, but there is only room
for three - the fiche card shows two pipes on the right hand side, one is a straight pipe and the other is a fuel inlet pipe - the same as the one on the left side. It appears it is optional (i.e. use straight pipe or inlet pipe) but the fiche card shows both as required. Again, only room for three pipes, not four. Bottom line, does fuel enter both sides or just left?
One last thing, do you think there could be an issue with the vacuum system for the fuel? The reason it will pump fuel when the line is in a cup (with the starter pushed) is because there is air for it to breath, but when we connect it, the vacuum is created and fuel cannot move?
I would really appreciate your help on this matter.
Thank you for your time if you need more info, please ask - you are my last source of help!
Matt Furney
Detroit, MI
AnswerHi Matt.
I much prefer the reliability of a repair manual.
Even when researching parts, the fiches are often wrong or lacking in detail. It took me 3 weeks to get a part ordered once because the fiche didn't show the part.
Here is what the repair manual that I have says to test the fuel pump; (bypassing the unimportant stuff)
2 Start the engine.
3 Pinch the vacuum line going to the fuel shutoff valve.
4 Shut off the engine and turn the fuel shutoff valve to the OFF position.
5 Remove the fuel pump relay from it's mounting bracket on the frame between the rear of the battery and the starter solenoid.
6 Disconnect the electrical connector from the fuel pump relay.
7 Connect a jumper wire between the white and black wire in the fuel pump relay electrical connector on the wire harness side.
8 Disconnect the fuel line going to the carburators.
9 Place the loose end of the fuel line into a graduated beaker.
10 Turn the ignition switch to the on position and allow the fuel to run out of the fuel line (into the graduated beaker) for 5 seconds. turn the ignition OFF.
11 Multiply the amount of fuel in the beaker by 12 (12x5=60 seconds). This will give the fuel pump flow capacity for one minute.
12 The fuel pump minimum flow capacity for one minute is 800cc (27.05oz) +/- 10%.
13 If the fuel pump does not flow to the specified capacity, the fuel pump must be replaced, refer to Chapter Six.
Make sure that the proceedures that you followed are exactly the same as those.
You said that the fuel pump is running when the starter is hit, but not with only the ignition on. This indicates a short since you have replaced the main components in the fuel pump system.
Check that and look for shorts in the electrical system, then let me know what you find.
Good luck and ride safe.
FALCON
