Help! Supra doesn't run right

[suprarx7nut]

Picked up the fuel pressure gauge today. Not to happy with actron at the moment. 6 days later still no progress in my order and I even sent an email to them like two days ago and got no reply.

Is there somewhere else I could possibly buy this bolt from?

Maybe this is a dumb question, but what bolt are you waiting for?

I tested the fuel system on my 90 1-2 years ago and the kit I rented from the local parts store provided every bolt/gasket needed to test. Maybe you're trying to do something a bit more complicated than a fuel pressure test?

 

[Abe's 1987]

https://actron.com/content/banjo-bolt-m1215
https://m.harborfreight.com/fuel-injection-pump-tester-62623.html
I ordered this banjo bolt tap and also bought this fuel pressure test kit. It is the cheapest set I've seen so far. The auto parts stores want $100+ just to rent the test kit. I know I will get the money back but just don't have the money to put up right now.

 

[3p141592654]

Would be a crap shoot, but this might work. Hard to say without trying it.

https://www.ebay.com/itm/FUEL-PRESS...NG-12MM-BOLT-KIT-1-8-NPT-FILTER-/151206591041

 

[Abe's 1987]

Spoke to soon. With no notifications or updates on the site they shipped out the banjo bolt. I just received it today in the mail. When considering it they did fast processing and shipping, but wish they could have informed me so i would have not freaked out.

Will test fuel pressure this sunday and let you guys know the outcome.

I also just ordered the egr vsv, egr vacuum modulator, coil pack harness, and iacv all used but tested good. Most likely will ship out on Monday, so should have it by the end of next week.

 

[Abe's 1987]

Ok tested fuel pressure. First i got idle to 800 rpm then double checked timing. Had to make slight adjustment. Now it's at 10 BTDC and once out of diagnostic mode timing advances to 15 BTDC.

With ignition on and fp and +b im getting 37 psi
At idle with fpr unplugged I'm getting 37 psi
At idle with fpr plugged im getting 37 psi
Snap throttle it drops from 37 to 30 psi
Wot when it has problems revving higher pressure fluctuates between 10 to 20 psi.

 

[3p141592654]

1) 37psi engine off and fuel pump on looks good. (spec is 33 to 40 psi)

2) Any condition with fpr vac line disconnected should show 36 psi (37 close enough).

3) Connecting fpr vac line at idle should drop pressure 6-9 psi. No change is not correct behavior. Either the vac line is not got vacuum of the fpr is bad.

4) ok, just to be sure, you disconnected and plugged the FPR vac line for the snap throttle tests? If you did, then the fuel system has issues. Snap throttle drop of more than 1 psi means a restriction somewhere.

5) 10-20 psi at WOT suggests fuel system restriction. Pressure should always be manifold pressure + 36 psi.

I think you have found your issue. Now you need to find the blockage.

 

[Abe's 1987]

ok, just to be sure, you disconnected and plugged the FPR vac line for the snap throttle tests?

If you did, then the fuel system has issues. Snap throttle drop of more than 1 psi means trouble.

Also, the lack of change at idle with plugged and unplugged vac line is not correct. Should change 6-9 psi going from unplugged to plugged.

Yes i did snap throttle test and fuel throttle test with fpr both plugged and unplugged same results.

 

[Abe's 1987]

Could this mean bad fpr?

 

[3p141592654]

Bad fpr does not explain low pressure at WOT. That is a restriction from tank to rail.

Does this car have mods to the fuel line or pump?

The lack of change in pressure with/without vac line could be fpr, or vac line issue. You can feel a strong vacuum at the vac line when disconnected at idle?

 

[Abe's 1987]

Ok so no mods to fuel lines or rail. I personally installed a new fuel filter myself. I forgot to check vac at vac line of fpr while it was running. Will check tomorrow for vac. I quadruple check the fpr vsv and it is operating as tsrm said it should be. No restriction from fpr vac line to vsv.

What does the fuel damper do?

I'm thinking about leaving the banjo bolt tap installed in until I get the car running right, would it cause any issues as per running and starting the car with it on?

 

[Abe's 1987]

With it building up pressure at idle, does that mean fuel pump is good?

 

[3p141592654]

You can leave the banjo bolt on permanently. Many cars have schrader valves on the fuel rail stock.

The pump appears to have enough juice to keep things pressurized at idle. But something is preventing enough fuel flowing under load. Should see 10V at the pump during idle. There is a resistor and relay in series with the pump. Under load the pump voltage increases to battery voltage by the ECU.

How is the rest pressure. When you shut the engine off it should remain pressurized for at least 5 minutes. If it doesn't, then the pump check valve is probably bad.

Since you replaced the filter, it could be the pump, the in tank filter sock, the lines (crushed or bent) or the dampener. Basically anything from the tank to the rail.

There was a thread on here with same symptoms as you, and the person claimed that it was the dampener that was bad. Replacing it fixed the problem. That seems weird, the dampener should not be restricting anything, but that was the claim.

 

[Abe's 1987]

You can leave the banjo bolt on permanently. Many cars have schrader valves on the fuel rail stock.

The pump appears to have enough juice to keep things pressurized at idle. But something is preventing enough fuel flowing under load. Should see 10V at the pump during idle. There is a resistor and relay in series with the pump. Under load the pump voltage increases to battery voltage by the ECU.

How is the rest pressure. When you shut the engine off it should remain pressurized for at least 5 minutes. If it doesn't, then the pump check valve is probably bad.

Since you replaced the filter, it could be the pump, the in tank filter sock, the lines (crushed or bent) or the dampener. Basically anything from the tank to the rail.

There was a thread on here with same symptoms as you, and the person claimed that it was the dampener that was bad. Replacing it fixed the problem. That seems weird, the dampener should not be restricting anything, but that was the claim.

So I still have more diagnosing to do. Without changing these parts can they be tested? My buddy is saying most likely the car sat for ahwile with bad fuel and the sediments are caught in the fuel pump and in rank filter sock. He said I'm most likely needing to change the fuel pump.

 

[3p141592654]

He could be right.

I would do a visual inspection of the lines looking for damage, kinks, etc. You can unscrew the dampener and check for blockage or sediment there. Also, check the voltage at the pump with the engine running.

You can also do a flow test. I cannot find any specs on what the factory flow should be. My guess would be 150 LPH. But we already know its low so its a bit pointless.

You have to drop the tank to get the pump out, so that is a bit of a last resort.

 

[Abe's 1987]

These things must be a one time use. I installed it once and tested and was going to permanently install it and it just snapped with no torque at all. I might call the company for a warranty on this.

 

[3p141592654]

That sucks. Mine hasn't broken yet.

 

[3p141592654]

Seems defective. You should call for sure.

It's too bad you don't know if the car ever ran correctly.

One thing that can block the rail is if the injectors are pushed too deep into the rail. The factory setup obviously doesn't have this problem but the injectors may have been worked on.

It is possible for the injector top of cylinder #6 to hit the pulsation damper threads protruding inside the rail as the two are aligned top of each other inside the rail. This can form a nice blockage. The injector grommets set the depth of the injector in the rail along with the three rail plastic isolators under the mount bolts. Another thing to consider. You could check that if you take off the dampener.

 

[Abe's 1987]

Yeah luckily I was able to remove the broken threaded part from the fuel rail. It would have been annoying to have to deal with that problem and my fuel problem as it is.

I will check the injectors and all fuel lines moslt likely tomorrow and will order a fuel pump if everything seems good. In your opinions which fuel pump is good for stock setup and potentially more power in the future?

 

[3p141592654]

The stock pump is fine for stock 440 cc injectors. If you go to 550 cc or bigger you will need an upgraded pump. Most people go with the Walbro 255. I am using the mk 4 supra pump. But it needs some wiring mods because it uses more current. The walbro is pretty much drop in. You will need to remove the J-tube restriction for any pump upgrades

 

[Abe's 1987]

The stock pump is fine for stock 440 cc injectors. If you go to 550 cc or bigger you will need an upgraded pump. Most people go with the Walbro 255. I am using the mk 4 supra pump. But it needs some wiring mods because it uses more current. The walbro is pretty much drop in. You will need to remove the J-tube restriction for any pump upgrades

Ok good question is where can I get a new stock pump from. I've heard of the walbro 255 but will probably stick with stock pump for now.