Carb sprays gas into the air?

[jfrancom101]

So I recently bought a 2500 gmc truck. originally it was a 6.2 diesel, but sice has been converted over to a 5.7 off of a 78 truck. It had a clogged undersized 2 barrel carb on it, and so I got a used edelbrock 1405. It came off of a running truck that someone was switching over to vortex heads so the carb should be fine, but while trying to start it it does this. I included a a picture of the old carb and the hose setup. I have the hose from the manifold and the spot for the brake booster blocked because my brakes hook up to the power steering pump and my I can't find a hose to hook up to the manifold.

messages_0.mp4

drive.google.com

This is the video of it that I uploaded to google drive
What could be wrong?

 

[WFO]

The only thing I can think of that would make fuel go the wrong way is an intake valve not seating.

 

[Bextreme04]

This engine ran before? Have you run a compression test to determine engine health? You can get this issue from a clogged exhaust as well, or a massive intake leak....

 

[jfrancom101]

This engine ran before? Have you run a compression test to determine engine health? You can get this issue from a clogged exhaust as well, or a massive intake leak....

I haven't done a compression test, but I did here it run before I bought it. It sounded pretty good, It seemed to be starving a bit for fuel, that why I got the new carb but I cant imagine what happened since then. When I changed the carb I also but a new used intake manifold on there, so there's that...

 

[squarelyfe]

I would do a psi test of your incoming fuel to that carb.

 

[jfrancom101]

I would do a psi test of your incoming fuel to that carb.

I might be able to do that soon. Right now I have cheap electric pump but while trying to start the truck I actually disconnected the wires, so there should still be volume inside of the carb, but zero pressure

 

[SirRobyn0]

@jfrancom101 the only thing that will make a carb spit fuel up in the air like that is pressure in the intake manifold. Only about 2 ways that can happen. #1. intake valve that is not sealing, and not just mildly that would be pretty bad. #2. firing order, in other words the wrong ignition wire on the wrong spark plug. The thing is most of the time that stuff will let fire into the intake manifold as well. So what you could have is intake valve that is not sealing well and to much fuel pressure causing to much gas in the manifold. Edelbrocks do not like more than 6psi of fuel pressure incoming to the carb. Most other carbs are more tolerant of higher pressure and all though the edelbrock came off a running engine who knows what the internals are like and how dirty it may or may not be inside.

If you had the distributor out, or removed the ignition wires (I assume you did, as you must have changed the manifold) double, triple check that firing order is on correctly. TDC the engine so you know where to put #1 and set up the firing order from there. Run a compression test on all cylinders. Check fuel pressure if at all possible. If that isn't practical install a cheap regulator with a "dial pressure set knob" and set it for 3psi, you may well need more pressure than that on the road, but it's enough to start, idle and run.

 

[jfrancom101]

@jfrancom101 the only thing that will make a carb spit fuel up in the air like that is pressure in the intake manifold. Only about 2 ways that can happen. #1. intake valve that is not sealing, and not just mildly that would be pretty bad. #2. firing order, in other words the wrong ignition wire on the wrong spark plug. The thing is most of the time that stuff will let fire into the intake manifold as well. So what you could have is intake valve that is not sealing well and to much fuel pressure causing to much gas in the manifold. Edelbrocks do not like more than 6psi of fuel pressure incoming to the carb. Most other carbs are more tolerant of higher pressure and all though the edelbrock came off a running engine who knows what the internals are like and how dirty it may or may not be inside.

If you had the distributor out, or removed the ignition wires (I assume you did, as you must have changed the manifold) double, triple check that firing order is on correctly. TDC the engine so you know where to put #1 and set up the firing order from there. Run a compression test on all cylinders. Check fuel pressure if at all possible. If that isn't practical install a cheap regulator with a "dial pressure set knob" and set it for 3psi, you may well need more pressure than that on the road, but it's enough to start, idle and run.

Those are both good possible causes. I hadn't actually considered, if the distributor was 180 degrees off, which looking back we did set it to TDC the first time and then attempted to start it, but then pulled it at one point and then I think it was almost lined up and we forgot to double check what stroke it was on. If it was sparking during the intake stroke then that could cause a premature combustion causing it to fire and pressure right into the intake manifold. That's definitely the first thing I'll do tomorrow and then see about the fuel pressure/ compression check.

 

[SirRobyn0]

Those are both good possible causes. I hadn't actually considered, if the distributor was 180 degrees off, which looking back we did set it to TDC the first time and then attempted to start it, but then pulled it at one point and then I think it was almost lined up and we forgot to double check what stroke it was on. If it was sparking during the intake stroke then that could cause a premature combustion causing it to fire and pressure right into the intake manifold. That's definitely the first thing I'll do tomorrow and then see about the fuel pressure/ compression check.

Yep. I think you have a likely culprit and good plan after that if it's not the distributor.

 

[Rusty Nail]

That guy is way underpaid.

We need moar pix but I have identified "well that might be your problem"...it looks like there is a weber on you truck's engine.
Betcha that's why it wont run rite.

You got nothin - that's wussy stuff.

xc_hide_links_from_guests_guests_error_hide_media

 

[Grit dog]

That guy is way underpaid.

We need moar pix but I have identified "well that might be your problem"...it looks like there is a weber on you truck's engine.
Betcha that's why it wont run rite.

xc_hide_links_from_guests_guests_error_hide_media

Well that was helpful.

 

[Grit dog]

Yep. I think you have a likely culprit and good plan after that if it's not the distributor.

Yes firing order, 180 out on distributor or timing off by a good amount.
So you got power to the distributor now I presume? (Don’t remember everything from your last thread but …)
Don’t keep trying to start it. Unless you don’t have exhaust, or a few more cranks and you could blow up your muffler. Literally
Go make damn sure you have the distributor installed right @ #1 tdc and firing order right.
It not only looks like this is the problem but sounds like it as well. Unless your battery is half dead. Sounds like the engine is fighting itself when you crank it.

 

[jfrancom101]

That fixed it! After I swapped it around and fired right up! Now I need to figure out how to work out the choke. It is electric and the truck has a manual cable... I'll need to figure that out

 

[SirRobyn0]

That fixed it! After I swapped it around and fired right up! Now I need to figure out how to work out the choke. It is electric and the truck has a manual cable... I'll need to figure that out

Well it's not both manual and electric. Obviously in 1985 factory setup would have been electric. If you want help with that just let us know!

 

[jfrancom101]

Well it's not both manual and electric. Obviously in 1985 factory setup would have been electric. If you want help with that just let us know!

I could definitely use some help with it. I assume that originally it had a switch in the cab to switch it to on choke or off? I thinking to fixed it i'd need to run a wire through the fire was to a switch, and then a second one back to the carb? I don't know where would be the right place to get the power from