Replaced entire fuel system from the filter back. Now no start.

[shift5]

'94 Blazer 350 (TBI) 5 speed manual 4x4.

Truck ran perfectly fine other than a pinhole fuel tank leak. Tore the tank out, found weak fuel lines, 25 year old truck, might as well replace the pump and sender while i'm in there and run new lines all the way up. So i did. GasTankRenu nylon fuel lines, new filter, tank, Delphi pump, sending unit. Everything from the bellhousing back is new.

So you can imagine my confusion when i put it all together, put fuel in it and crank no start.

I prime the key and the fuel pump RUNS. Clear as day. It was loud and then I put fuel in it and now it's quieter. Has 5 gallons of gas in it.

Cranked and waited probably 15 times. Not so much as a sputter.

Put a spark tester on it, confirmed spark. I don't have any starter fluid so I didn't try that.

Where to begin diagnosing? I understand these TBIs have apparently no fuel pressure test valve.

 

[evilunclegrimace]

Check for fuel pressure. I had a factory new sending unit that was wired incorrectly. The pump ran backwards. It took me a while to figure that one out. I put a pressure gauge on it and no pressure but the pump was running

 

[Supercharged111]

You ran a 3/8 and a 5/16, right? So no chance of the tubes being hooked up backwards?

 

[shift5]

You ran a 3/8 and a 5/16, right? So no chance of the tubes being hooked up backwards?

I didn't plumb anything. Fittings pre installed, so I don't think it could have been mixed up.

 

[shift5]

Check for fuel pressure. I had a factory new sending unit that was wired incorrectly. The pump ran backwards. It took me a while to figure that one out. I put a pressure gauge on it and no pressure but the pump was running

What brand? How do you test pressure without a valve?

 

[arrg]

There are pressure testing adapters that screw in place of the fuel filter and ones that screw in between the supply line and the TBI.

 

[Supercharged111]

I didn't plumb anything. Fittings pre installed, so I don't think it could have been mixed up.

Did you not run new lines along the frame? Were they not different sizes? If so, then this is a non issue.

Here's how I set up an FP gauge on my TBI motor. I used this fuel pressure adapter fitting. You'll have to scroll down to see it as a direct link is not very intuitive.

http://www.rvmorsemachine.com/product.htm

 

[east302]

I’m not sure if it’s possible, but is the fuel filter reversed?

I wonder if you have a pocket of air in the line. I’m not familiar with how the TBI is plumbed, but maybe crack the fitting at the firewall (presumably the high point) and see if it leaks out. Or connect a hose and bucket to it and turn the key on for a second or so.

If there’s no fuel on the discharge side, maybe something is blocking the suction in the tank.


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[shift5]

There are pressure testing adapters that screw in place of the fuel filter and ones that screw in between the supply line and the TBI.

Yeah i know about those. Have to get one though. I want the truck on the road!

Did you not run new lines along the frame? Were they not different sizes? If so, then this is a non issue.

Here's how I set up an FP gauge on my TBI motor. I used this fuel pressure adapter fitting. You'll have to scroll down to see it as a direct link is not very intuitive.

http://www.rvmorsemachine.com/product.htm

All new lines along the frame. Different sizes. So correct, I don't see how they could have been mixed up.

I’m not sure if it’s possible, but is the fuel filter reversed?

I wonder if you have a pocket of air in the line. I’m not familiar with how the TBI is plumbed, but maybe crack the fitting at the firewall (presumably the high point) and see if it leaks out. Or connect a hose and bucket to it and turn the key on for a second or so.

If there’s no fuel on the discharge side, maybe something is blocking the suction in the tank.


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That'll probably be the next step.

Really can't be anything blocking in the tank, as the tank is brand new.

 

[east302]

Really can't be anything blocking in the tank, as the tank is brand new.

I’ve never had to look at one (knock on wood) but think they have a strainer or something on the intake, so a manufacturer defect is kind of where I was going with it.

I’d definitely try cracking and venting it before dropping the tank again. Good luck with it.



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