1G Slow er crank

[Bigmike4g63t]

This past weekend I installed a walbro 255 and completed a fuel pump rewire. Since then it takes a few seconds to crank. Before it was nearly instant. Now it turns over maybe 15 times before cranking. Any ideas? Only thing I can think of, and I'm too tired to go out there currently, is that maybe I need to turn the key to the on position and wait a few seconds for the pump and then try it?

 

[pauleyman]

You likely have at leak at the pump dropping fuel pressure as the car sits. Does it start instantly if you shut it off and start again?

 

[Bigmike4g63t]

Yes, it does.

 

[99dsmer4g63]

You have a leak somewhere. A leak doesn’t mean you’ll see fuel visibly leaking out either.

-Daniel

 

[Bigmike4g63t]

The only line I opened would be the fitting on the fuel pump assembly on top. Maybe I need to open it up and check that out. Thx!!

 

[99dsmer4g63]

It could even be in the tank. Where the pump meets the sending unit housing. On a 2g there is an o ring in there. Not sure on a 1g though. Your fuel pressure seems to be bleeding off though. Which in return causes the hard start.

Think of it like taking a straw out of water and keeping your finger over the top of it. Water will not come out of it till you move your finger and allow air to replace the water. This is what your fuel system is currently doing. Allowing air to replace the fuel. Where is the question though.

Check everything you did. Was this a new walbro 255? Or a used one or a knock off?

-Daniel

 

[Bigmike4g63t]

Its a walbro. I will check the outside line first. That will be the easiest to fix. Not that it is hard to pull the pump anyways. Only takes a few minutes. I replaced the o-rings. I put the taller spacer between the unit and the pump.

 

[Mech Addict]

While that cause seems very logical, doesn’t the pump start running with the key in the run mode? If one were to wait a bit before cranking, the line should refill mostly, and take less starting cranks.
This would simply help confirm the diagnosis. Wherever pressure is escaping (likely in the tank, or you’d know where the leak was), you want to find it and seal it properly.

 

[pauleyman]

While that cause seems very logical, doesn’t the pump start running with the key in the run mode? If one were to wait a bit before cranking, the line should refill mostly, and take less starting cranks.
This would simply help confirm the diagnosis. Wherever pressure is escaping (likely in the tank, or you’d know where the leak was), you want to find it and seal it properly.

No. Fuel pump runs when cranking. Not key on.

 

[Bigmike4g63t]

Thanks for clearing that up. I had a 85 mustang gt and that car had lots of fuel pump issues due to rust in tank and I had to replace the tank. Anyways, turning the key on and you could hear the fuel pump turning on.

Could it be losing pressure around the pump assembly gasket on the top of the tank?

 

[pauleyman]

Could it be losing pressure around the pump assembly gasket on the top of the tank?

No. That isn't pressurized. The most likely culprit is at the pump itself in my opinion. It has been discussed many times.

 

[pauleyman]

You can prime the pump manually and then try and start. If it starts you know for sure it's a fuel pressure issue. Some of us don't use an oring any more. You can fire it if you have ecmlink or with the fuel pump check connector on the firewall. Or bump starter enough to just get a rev or two. That will engage the pump circuit. Won't stay engaged but once or twice is enough to pressurize.

https://www.dsmtuners.com/threads/o-ring-on-fuel-pump.475316/

 

[99dsmer4g63]

I wanted to add that had a similar issue once. I had a cheap fuel filter on my car and never seen any evidence of fuel actually leaking but could smell it in the engine bay. Once the filter was replaced with a quality one the issue went away.

I never seen any fuel leaking out or could even get a wet spot in my fingers when feeling around the fittings on it. It could be just enough to allow air in after sitting and not drip fuel.

-Daniel