fuel pump issue

New to forum just picked up 96 750 at auction. Fuel pump not pumping when ignition is on. I checked relay and red/yellow wire and blue black wire (into relay) are hot when ignition is on. Blue black wire and green (ground?) from relay to pump are not hot with ignition on. I'm thinking relay is bad. I'm guessing the blue black wire to pump should be hot when ignition is on. I tried supplying 12v to blue black wire on pump and grounding the green, no response from pump. Am I on the right trrack? Thanks in advance.

 

The green should be a common ground and the blue black switched from relay with engine turning over. If the fuel system is primed the pump will only fire even if jumped when supply is required, disconnect the output line and verify your power and ground and check again, if nothing then look at or for a pump.

 

Relays fail far more often than pumps themselves. Try the relay bypass illustrated in the FSM, and the pump should click when the key is on. Open a bowl drain screw so there is need for more fuel.

One quick, easy check on pump is to place meter leads on the 2 wires coming from pump, checking for a few ohms resistance. No continuity at all means the pump's shot.

 

You can pull the pump and hook it directly up to a battery to test. Under the back cap is set of contact points that close when the pump diaphragm senses a pressure drop. That's why the pumps pulse instead of constantly run. Often these points wear out just like ignition points on an old motorcycle and need to be replaced.

If the pump is stuck you can try squirting some WD in the inlet to try and free it.

 

Thanks for the input. I've got the pump working now, I can't check psi but I'm getting good flow. I can get the engine to fire on choke, Idle 5-10 sec and then die, like the jets are plugged. I tried to pull the carbs from the intakes to check the jets but the carbs don't want to release from the stiff rubber boots, I'm afraid I'll split a boot or not be able to reinstall the carbs in the old boots. I'm spraying some carb cleaner into the fuel bowl drain holes. I'll also try some gas with techron to see if I can get more fuel thru the carbs. The fuels bowls are filling so I know I don't have a stuck needle valve. I'll let you know how it goes tomorrow. I'll also need a slip on exhaust, my bikes missing the stock slip on, any suggestions? Thanks again.

 

if the boots are that bad replace them... chances are the idle jets are plugged.. How long has the bike been sitting? If you got it at an auction I am willing to bet it has been a while. at this point you should clean the tank change the fuel filter and clean the carbs as well as change the boots... the bike will be running like a champ in no time.

 

Make sure the boot clamp screws are backed way off--just having them a turn from tight is not nearly enough. The boots have to really expand to get over the lip and you don't want the clamp fighting you. Then squirt some lube between the boot and the intake using a small screwdriver to pry back the lip to get the lube started in there. Then heat the boots with a hair dryer and pry the whole rack up from the rear--pry bar and block of wood.

 

not sure if it is the same for the 96 as it is for the 86, but remember when you put the boots back on there actually is a specific way they go on...new ones wil have arrows and everything...

 

Your year of VFR was the very easiest to get the carbs off given the design of das boot, what Kennybobby said is ringing true, make sure they are loose, they should come off pretty easy. Not at all like gen 1 or gen 2.

 

Loosen BOTH clamps on each boot cuz it may come off easier from one end than the other so you have better chances that way.

If you can warm up the engine for a few minutes, boots will soften and make removal easier. Start by pushing-pulling-lifting carbs so you can see them rocking a bit by pulling up sharply at each rear corner of the airbox plate. Helps to concentrate your lifting efforts to one corner of the airbox at a time, gradually working around the square lifting a fraction at a time till they finally pop. They need gradual persuasion by pulling, light prying, pushing, wha'eva, just get them moving around a bit b4 expecting to get them off using lube spray and sweat, alot of sweat with hard, old boots, making you very thirsty..... arty2: :drinker:

 

Thanks I got them off with lube and a heat gun. They're very hard, I'll put new ones on for the reinstall. Thanks