Fuel pressure

[Jaguar_5]

Hey guys, i have a quick question

How long does it take for a walbro fuel pump to pressurize the fuel system?

My AFPR takes awhile to register pressure, and it slowly goes up

I am abit concerned! But not sure if this could be normal if the car's been sitting for awhile?

 

[suprafanatic]

should be pressure all the time if car is runnnig

 

[Jaguar_5]

Ok, let me make this abit more clear since I forgot to mention some details

The car is not running yet, and I'm talking about having system that's been sitting empty for a long time, and jumping FP and B+

I can't really hear fuel coming into the fuel rail, but it does build pressure if I give it some time, and there are no leaks...

 

[suprafanatic]

so your connecting the signals so the pump comes on? hmm.. i would say keep tying it and see if the pressure builds up anymore.. if not the car just might need to be running.. do what you need to to get the car running and worry about it then, cause it might be alright once the car is running

 

[Jaguar_5]

The pressure does come up eventually, it just takes a few minutes to get to full pressure, seems strange to me, and I can't even hear any fuel flow...

I did try and start it, with no luck. There was what I think was a backfire though, there was a pop and my friend saw some smoke come around the TB area, and I smelled fuel, he said I lost a good amount of fuel pressure when that happened?

I pulled plug #1 and it smelled like fuel and looked a little wet and oily.

I'm not sure if it was just about to start when the battery lost it's juice, or if my timing is off... I thought I wasn't getting spark (skeptic of my cables) but then what could that pop be otherwise?

The battery is dead, and on a charge right now, I don't have another vehicle to jump it atm (i'm 'borrowing' the battery from my DD)

 

[Jaguar_5]

After fixing the timing (off by 1 tooth) i was able to get it to start and run briefly, but then I confirmed that my hunch was correct, there is something not quite right with my fuel system

The car will start but then pressure drops until it won't run anymore

 

[supraguy@aol]

How long does it take to run low on fuel pressure? Is it immediate?
You definately need a fully-charged battery to determine what's going on.

 

[Jaguar_5]

How long does it take to run low on fuel pressure? Is it immediate?
You definately need a fully-charged battery to determine what's going on.

The battery was fully charged the last time I tried it

The amount of time it takes to run low on pressure depends on if it even was at full pressure! My longest idle, I jumped FP and B+ until I had over 30 psi when we started it, it lasted about 1 minute until it died, i had my friend start it I was outside watching the fuel pressure drop to nothing.

I've done the 12v mod, and the stock wire triggers a relay, the pump has a new 10 gauge wire

The walbro pump, and toyota filter, are both effectively new

 

[SupraDreamPDR]

I am currently having this same problem with my recently upgraded fuel system on my '90 (Walbro, 550s, 12v mod, AFPR with all Driftmotion S.S. hoses). When I jump FP and B+ it takes forever to build pressure... my battery is also slowly losing juice from sitting so long. Could the battery be an issue with these problems?

 

[7MGTEsup]

Sounds odd I have a walbro GSS341 and jumping fp b+ gives me instant fuel pressure. Sounds like you have a faulty pump or a split in the hose inside the fuel tank.

 

[ForcedTorque]

You said you smelled fuel. Is there a leak of any kind?

 

[Supra87T]

Sounds odd I have a walbro GSS341 and jumping fp b+ gives me instant fuel pressure. Sounds like you have a faulty pump or a split in the hose inside the fuel tank.

I second that. Could also be a clogged fuel line also or something else keeping the pump from keeping the pressure up. Fuel pressure should build pretty quickly and you should also be able to hear the fuel flowing through the rail. How old is the AFPR?

 

[grimreaper]

I am currently having this same problem with my recently upgraded fuel system on my '90 (Walbro, 550s, 12v mod, AFPR with all Driftmotion S.S. hoses). When I jump FP and B+ it takes forever to build pressure... my battery is also slowly losing juice from sitting so long. Could the battery be an issue with these problems?

charge the battery and find out, or swap in another one

 

[Jaguar_5]

I have narrowed it down to a clog in the banjo fitting that connects to the bottom of the metal union coupler that bolts onto the engine mount

For more details check my build thread

Thanks for the input guys!