yeetennessee

so the pickup is a 22re, and ive done just about everything i can think of to fix this issue, ive redone the fuel pump like 3 times and ive cleaned out lines and the tank, rebuilt the injectors, but still the truck will lose power and buck at half of a tank. like the fuel is immediately cut off but there's still half of a tank in it.
i finally got the idle sorted out and a new brake booster in it, (other problems, ) and after replacing the ignition coil it runs much better, it pulls better too. does not bog down at 45 mph. im almost certain the the fuel pump is good because i can hear it running at idle. i dont know/ have a way of checking the evap canister, but if anyone knows what is going on with it then please let me know. i highly doubt that the pump just isnt low enough. but i guess its possible.

scope103

Welcome to YotaTech.

You can do a very simple test of fuel flow by removing the FPR returning line and replacing it with a 6mm clear vinyl tube to a suitable container. There is no spec for this, but running the fuel pump with the jumper I get about 1/2 liter/min. You could try a before-and-after with the tank full and at the point where bucking starts.

This won't tell you everything about flow at load. Also, I'd be wary of trying this with the engine running, as you have fuel splashing and plenty of ignition sources.

JoeS

Fuel pressure regulator? Check vacuum hose connections, leaks, cracks...etc. You did replace the brake canister that is also a vacuum operated unit, so maybe there is a vacuum leak somewhere else.
https://www.ebay.com/itm/17428323635...MAAOSwOXJevZJy

yeetennessee

i have replaced the brake booster, the one that is connected to the master cylinder. but that didn't help the fuel issue. ive talked to a friend lately nd turns out im missing one of the vacuum line things on the intake, the L or T shape one with the spring, is just missing on my truck. but no i haven't replaced the fuel pressure regulator. that could/should be the problem. thanks for the link.

yeetennessee

so i could check the flow with the key in "prime" position and a clear tube, i may just wind up putting a fuel pressure regulator on it if im gonna get back there. i assume the flow will be slow or nonexistent if the regulator is bad?

scope103

There is no prime position; the fuel pump runs with the key to STArt, and then continues when the VAF senses intake flow. To make the fuel pump run with the engine not running you use the diagnostic jumper. Your '88 has a different setup than later models, but you can find all about it here: https://www.4crawler.com/4x4/CheapTr...shtml#FuelPump

The pump runs at a constant speed, and the FPR "returns" whatever it doesn't need to hold the pressure in the rail. With engine running faster (using more fuel), there is less flow in the return line. If the test flow is slow, either the pump is also too slow to keep pressure in the rail when the injectors need it, OR the FPR is holding too much pressure in the rail. To tell which it is you need a fuel pressure gauge.

The purpose of the flow test is a simple test of the fuel pump; if the pump is bad, there will be no return flow, and the rail will never reach the necessary pressure.

yeetennessee

yeah that sounds correct, by "prime" i meant "start" but with no clutch or clutch override button, so just the pump will run. i know someone had/ done/ is still doing a hack job of fixing it because there are rubber lines just hose clamped onto the hard lines under it, near the frame on the passenger side. so i can unhook those and see what happens away from anything that could cause a fire. but it sounds like ill have to do this test before i put the regulator in. that ive already ordered.

i sure am responsible with the budget for this project. lol

scope103

Replacing the FPR without a fuel pressure test of some sort sounds like the "Parts Cannon."

yeetennessee

well, mostly

RAD4Runner

https://www.yotatech.com/forums/f199...l#post52312190