Hard start from cold

[BayouBiker]

Originally Posted by PeterH-350LE

Not trying to guess, just have to be able to connect a fuel pressure gauge, so I ordered an inline gauge port to connect the same.
Until it arrives, to continue our guessing game, the facts are:
It fired up on the first crank for 10 month, cold or hot with a new external fuel pump that apparently does not have an internal check valve. (Walpro GSL-392)

Now it takes progressively longer to fire it up and when i turn the key to ign on and observe the throttle body injectors, i hear a hissing sound, that appears to be a leak.
Oh, and it accelerates great and runs super.
And, I just went outside and it fired up on the second crank. So.....

The Walbro fuel pumps are positive displacement and check valves are part and parcel of the pump design. That it holds pressure for a day is adequate. You should have a 30-40 micron filter/strainer between the tank and pump to catch anything that would get stuck in the pump valves and then a finer filter between the pump and injectors.

The hissing sound is interesting. Do I understand this is with the ignition on but the engine not running? Describe this a bit more.

[PeterH-350LE]

Originally Posted by BayouBiker

The Walbro fuel pumps are positive displacement and check valves are part and parcel of the pump design. That it holds pressure for a day is adequate. You should have a 30-40 micron filter/strainer between the tank and pump to catch anything that would get stuck in the pump valves and then a finer filter between the pump and injectors.

The hissing sound is interesting. Do I understand this is with the ignition on but the engine not running? Describe this a bit more.

You (and Bob M) are correct, I contacted Walpro and they do have an internal check valve. I do have a canister type fuel filter between the tank (ACD GF157 ) and the pump and a 10 micron inline between the pump and the rail.
To best describe the hissing sound, with only ignition on and the fuel relay engaged, I hear a sound that would resemble the sound of compressed air escaping at ~10 psi . Of course it stops after the relay kicks out, but will continue every time I turn ignition on.

[BayouBiker]

The early 1990's GM 454 fuel injection design includes a pressure regulator with a continuos bypass that returns fuel to the tank. Hopefully the regulator is what you are hearing, and it would suggest the pump and filters are likely fine and given what you describe in terms of starting make me want to suspect the regulator has the pressure a bit low as was previously suggested, but the pressure gauge will confirm that. Wish I could be more helpful but I can't think of any other way to test the regulator.

[PeterH-350LE]

Originally Posted by BayouBiker

The early 1990's GM 454 fuel injection design includes a pressure regulator with a continuos bypass that returns fuel to the tank. Hopefully the regulator is what you are hearing, and it would suggest the pump and filters are likely fine and given what you describe in terms of starting make me want to suspect the regulator has the pressure a bit low as was previously suggested, but the pressure gauge will confirm that. Wish I could be more helpful but I can't think of any other way to test the regulator.

Thanks, hopefully by Saturday I will be getting off this scaffolding to work on the 350 and check the fuel pressure Sometimes other pressures keep you from doing stuff.

[jeffmc306]

Peter, that’s quite a view! Greek Orthodox Church? Beautiful.

[PeterH-350LE]

Originally Posted by jeffmc306

Peter, that’s quite a view! Greek Orthodox Church? Beautiful.

yes, St Elias Orthodox Church. We are just doing restoration work, painting, some gold leafing and pearlized venetian plaster in the Narthex.

The church is adorned in the Byzantine style with many icons of Christ, the Virgin Mary, and the Communion of Saints. Very impressive work done by an icon muralist, whose name I do not know. Quite an honor to be asked to work!

[PeterH-350LE]

Originally Posted by BayouBiker

The early 1990's GM 454 fuel injection design includes a pressure regulator with a continuos bypass that returns fuel to the tank. Hopefully the regulator is what you are hearing, and it would suggest the pump and filters are likely fine and given what you describe in terms of starting make me want to suspect the regulator has the pressure a bit low as was previously suggested, but the pressure gauge will confirm that. Wish I could be more helpful but I can't think of any other way to test the regulator.

I forgot to mention that after cycling the ignition a few times without starting the motor, I would get a whiff of gasoline odor. I wasn't able to determine if it came from the injectors or the regulator gasket. Should it not be a tight system until powered up?

[Magnet18]

Originally Posted by PeterH-350LE

I forgot to mention that after cycling the ignition a few times without starting the motor, I would get a whiff of gasoline odor. I wasn't able to determine if it came from the injectors or the regulator gasket. Should it not be a tight system until powered up?

I don't know about the OEM systems, my system fires a "priming shot" after turned to ignition but before cranking, to help with starting

See I you can hear/feel/see the injectors click when you turn the key

[bkahler]

Originally Posted by Magnet18

I don't know about the OEM systems, my system fires a "priming shot" after turned to ignition but before cranking, to help with starting

See I you can hear/feel/see the injectors click when you turn the key

I don't believe the OEM system has a priming shot. I've not noticed it on mine nor have I any seen any documentation implying that it does. I do know it has something like a 2 second pump cycle to pressurize the system if you turn the ignition to the ON position. Mine does come up to pressure in that 2 second period.

[bkahler]

Originally Posted by PeterH-350LE

I forgot to mention that after cycling the ignition a few times without starting the motor, I would get a whiff of gasoline odor. I wasn't able to determine if it came from the injectors or the regulator gasket. Should it not be a tight system until powered up?

I've not noticed a gasoline smell on mine. Later today if it warms up enough I'll cycle my ignition switch a few times and check for odors.

[BayouBiker]

As Bkahler, described, the cold start control is supposed to spray a primer shot and then on the TBI models just a richer formulation till it warms a little. On port injection models there is often another cold start injector in the manifold or throttle body. If the regulator is good, I was going to suggest the cold start components might be an issue, again based on the symptoms that cycling a couple few times helps. Plugged injectors causing the prime to be light might also be the issue, but the pressure should be checked first as someone else had suggested instead of my earlier suggestion to just clean the injectors.

Beautiful Church, very impressive to be involved in that kind of work!

[PeterH-350LE]

Nope the throttle flaps stay dry when cycling ignition. My pump cycle is more like 5-6 seconds.

[BayouBiker]

That's interesting. I may have to look at the control diagrams closer. Perhaps it does not prime until the engine begins to crank. I am not sure. The fuel regulator and accumulator has a diaphragm I don't know if it is vented or plugs into the vapor recovery. That may be the source of a gas smell. Otherwise I'd suspect a leak.

[Magnet18]

Not sure how the regulators are designed, but if they have a rubber diagram, perhaps fuel is leaking past it to the unsealed portion of the housing, that's what was happening on mine. Could be a totally different design

[BayouBiker]

They are all the same basic design, good catch magnet18.

[Boom Sounds]

Originally Posted by PeterH-350LE

Just had tank cleaned, new filters. Same problem before and after having tank cleaned. Like I said it coincided with me replacing fuel pump relay and continued to have the same symptoms when I reinstalled the original relay.

As far as i can tell, pressure drops after sitting for a few days, but not overnight.

As far as the throttle body rebuilt goes, it is something I wanted to do anyways, since the last person installed some cheapo injectors from Autozone. They are not even listed as a parts option at Rock Auto. I ordered some OEM ACDelcos

I didn't order one of these, but you might want to look into it. When I was replacing mine, I as getting conflicting information relating to part numbers, so I ended up speaking to someone at Delco who clarified the correct numbers. I think some were different to the ones the Delco site served up using my VIN.... http://marine-performance-parts.com/...843505774.aspx

For info - should anyone ever need TBI info. I was given this guy's name as a contact. Seemed like good people who know TBI stuff inside out.
John Razzouk
Carburetor Specialist
5715 N Commerce Ct., Suite 200
Alpharetta, GA 30004-4178
https://www.carbs.us/about

[PeterH-350LE]

Throttle body disconnected. May not have the right adapter to connect the gauge with throttle body connected. Here is the scary part, Bob, the supply line was barely hand tight

[Magnet18]

How long does it take for pressure to leak down, and does it come back in the few seconds the pump runs after you turn the key?

[PeterH-350LE]

Originally Posted by Magnet18

How long does it take for pressure to leak down, and does it come back in the few seconds the pump runs after you turn the key?

30 minutes, pressure dropped 40, turn key on, pressured stayed at 40, didn't go back up to 60.

[Magnet18]

Originally Posted by PeterH-350LE

30 minutes, pressure dropped 40, turn key on, pressured stayed at 40, didn't go back up to 60.

That's odd
Did you hear the hissing noise?
Did cycling the key a second time do anything?