Hi, I have just purchased a 75 Hilux with a 20r. It has an aftermarket fuel pump that the previous owner installed after the in tank fuel pump went out. The problem I have is that the pump running all the time as long as the key is on even with the engine off. It runs rich and when I turn off the truck ill get a pretty audible backfire. I have no catalytic converter on the truck. Is there a fuel pressure regulator for this truck? Im not very well informed on electric fuel pumps as my last vehicle, a datsun 720 had a mechanical fuel pump. If someone could help me out or guild me in the right direction to an article or write up id appreciate it. Thanks!!

 

Does your 20r have a weber? I believe the webers want a very low fuel pressure somewhere around 2 psi. I'll do some searching

 

The pump should run all the time and if the current pump is too strong you need a regulator.

this has some info

 

Not only should you have a pressure regulator, you should also have a oil pressure cutoff switch. The cutoff switch is a safety feature and will kill power to the pump if the engine is not running. If your truck came from the factory with an electric pump, there should be circuitry that incorporates an oil pressure switch. It sounds like the original owner bypassed the circuitry and just grounded the pump directly.

 

They probably bypasses the fuel pump regulator when they did the pump.. Mines on all the time because my regulator was ****ed up and I bypassed it and have a switch to turn it off..

 

The truck does not have a weber, its still the stock carb. Its a rebuild.

It seems like the fuel pump is grounded to the relay under the dash on the drivers side. Ill try and find the oil pressure switch.where would I find the return line, or where would it be hooks up? And where does the regulator get the vacuum from?

 

I think they did bypass it. At the same time, if I just cruise around town I only get some backfiring just little pops in between but if I get it on it a bit it backfires when I turn it off.

 

Sounds more like your carb needs some tuning.. Running too rich can cause some backfiring.

 

If a fuel pump has no regulator wouldn't it be overflowing the fuel bowl in the carb and going down the throat of the carb through the top holes causing it to run rich? When I got the truck the idle mixture screw was 6 turns out, so I went in and now it is only 1 1/2 turns out. I will check the throttle stop and see if it is too far in causing it to be a little accelerated.

 

Sometimes yes, sometimes no. I don't have a regulator and mine runs just fine.

 

Ive been looking for a return line and the fuel regulator and can not find it. Where are they located? I looked online but could not find it.

 

On a 75, it could come factory with an electric in tank pump or mechanical. Stock electric had no regulators or return line. Just a flow line and air vent. I have a 78, put a weber and never had a problem with overflow.

The popping is a sign of too rich causing fuel to go boom in the tail pipe. Try adjusting the timing to 10-14 before top dead center (BTDC) that will help. Also make sure the idle speed screw isn't set too low or that will add to the "popping" when letting off cruising around. Try the same conditions but leave about 5-10% throttle pressure on the pedal and see if that little extra keeps it at bay.

A high output coil like an MSD blaster 2 or Accel super coil would help burn the mixture better too and idle smoother as well as rev smoother. Some NGK V power spark plugs and better wires like Taylor 8.2 exact fit 22r set finish off the mix. I always upgrade ignitions as one of the first mods even before bigger carbs and exhaust.