fuel pump

So im working on a 1990 b2200 and it has power going to the fuel pump but as soon as i connect the fuel pump theres no more power what would you guys recommend the pump works if i hook up constant 12v+

Is this truck carbureted or fuel injected?
Everything else on it completely stock?

It's Carburated and yes its completly stock i checked the voltage on the fuel control unit/relay yellow wire on has 10.34 and black and white has 11.46 same as battery

Is your truck an automatic? If it's carbed and you are talking about power going to the fuel pump it has to be, right? Carbed 5sp trucks have a mechanical pump and don't need "power" because they re operated by the camshaft.

Yes carbed automatic yes im talking about the power going to the fuel pump

I think you have a poor wire or connections somewhere in the fuel pump wiring, and it cannot supply the amperage to the fuel pump, so the voltage drops off.

Think of the wiring as a garden hose with a kink in it and a trigger style spray nozzle on the end. The hose still reaches full pressure, but drops off to no pressure when you pull the trigger. You have a "Kink" in the electrical line somewhere, usually as a corroded, or poor connection.

No, I wouldn't recommend hooking the fuel pump up directly to 12-volt switched power, the relay and circuit are the way they are for a reason. No - I don't know exactly what that reason is...

On the other hand: on old VWs some sometimes add on an electric fuel pump, and they do wire up directly to switched 12 volts positive.

I think we had a communication breakdown as a result of punctuation going AWOL. I don't think he was advocating direct wiring his pump. Here is what I think he was try to say (after the punctuation has been court marshaled and returned to active duty):

"So im working on a 1990 b2200 It has power going to the fuel pump but as soon as i connect the fuel pump theres no more power What would you guys recommend The pump works if i hook up constant 12v+"



Mini, when you say "...as soon as I connect the fuel pump, there's no power."
How are determining there is "No Power?" Because the pump doesn't run? Or because the voltage is no longer present after you connect the pump?

Have you jumped wires at the relay? If not, then you shouldn't even have power at the pump unless the engine is running? What color wire do you have for the power wire on the rear harness (truck harness) going to the fuel pump? Black/Red Stripe?