454 dies over 1800RPM loaded

[beech2000]

Engine is a 2019 Michigan Motors Gen 5 454 long block with the original 1990 manifold and Q-jet carb which is suspect.
Ignition is New Delco Voyager EST with new plugs, cap, rotor and wires.
105 hours on the new port and star engine and ignition system.
Seems like port engine is running out of fuel in bowl. Star engine is same configuration and runs fine.
I've replaced the carter fuel pump and swapped with the pump from star engine. No change.
Engine idles funny since this started last year. Thoughts?

 

[alldodge]

Have you checked compression?
Check fuel pressure while running

 

[beech2000]

Have you checked compression?
Check fuel pressure while running

Neither.
Compression check I can handle. Not sure how to go about fuel pressure test while running. The line from the carter fuel pump is a double inverted flared 3/8" steel line. I'll start looking for an fitting that would allow for a 1/4" NPT fitting be plumbed in to my fuel pressure gauge. Thanks and kinda knew fuel pressure would be a discussion item. The compression check was not due to only 105 hours but will be now. Thanks

 

[alldodge]

Normally a new motor would be solid, but if fuel system (carb in this case) is running lean it can warp valves and damage pistons

You could do a easier test with a vacuum gauge on the line coming from the fuel tank to the fuel filter. If you get less than 0.5 Hg then your good. More than that there is most likely a clogging in the fuel tank or antisiphon valve.

If no more than 0.5Hg then need to look at the pump to carb

 

[beech2000]

Normally a new motor would be solid, but if fuel system (carb in this case) is running lean it can warp valves and damage pistons

You could do a easier test with a vacuum gauge on the line coming from the fuel tank to the fuel filter. If you get less than 0.5 Hg then your good. More than that there is most likely a clogging in the fuel tank or antisiphon valve.

If no more than 0.5Hg then need to look at the pump to carb

Great info but scary.
Now I have to figure how to plum in vacuum gauge on the inlet side.
Never easy
What size fittings on the lines to water separator using a 3/4" wrench? Still 3/8" or 1/2" lines?
Need to know this in order to find a tee that will work

 

[beech2000]

Normally a new motor would be solid, but if fuel system (carb in this case) is running lean it can warp valves and damage pistons

You could do a easier test with a vacuum gauge on the line coming from the fuel tank to the fuel filter. If you get less than 0.5 Hg then your good. More than that there is most likely a clogging in the fuel tank or antisiphon valve.

If no more than 0.5Hg then need to look at the pump to carb

Question.
Can a vacuum gauge be used to perform a fuel pressure test on the inlet side of the fuel pump without the engine running? That is engine not demanding any fuel such as idle in slip but a running engine?
If so then I could simply jumper wire the pump to on and use the 3/8" in NPT inlet fitting on the carter electric pump to check for vacuum there right?

 

[04fxdwgi25]

Vacuum gauge needs to be on a running engine to be of any use. If going through all this, I would use a pressure gauge on the outlet. That will not only tell if the is fuel pump operation, but will verify it is correct or not.

Please be careful working on the fuel system and have a fire extinguisher at the ready.

 

[alldodge]

As mentioned need motor running under load to check vacuum

Vac fuel pressure Gauge

The test gauge measures both. I mentioned Vac because it can be connected easier because it's placed in line with the rubber fuel line coming from the tank. Fuel pressure at the carb is best method and requires a fitting make up between the 3/8 inverted flare at the carb. Most times all fittings can be found at local auto parts store

 

[ROY WILLIAMS]

Engine is a 2019 Michigan Motors Gen 5 454 long block with the original 1990 manifold and Q-jet carb which is suspect.
Ignition is New Delco Voyager EST with new plugs, cap, rotor and wires.
105 hours on the new port and star engine and ignition system.
Seems like port engine is running out of fuel in bowl. Star engine is same configuration and runs fine.
I've replaced the carter fuel pump and swapped with the pump from star engine. No change.
Engine idles funny since this started last year. Thoughts?

FUEL FILTER AND THE WATER FILTER . Q-JETS CARB
SO 105 HOURS FUEL FILTER !

 

[Bondo]

Engine is a 2019 Michigan Motors Gen 5 454 long block with the original 1990 manifold and Q-jet carb which is suspect.
Ignition is New Delco Voyager EST with new plugs, cap, rotor and wires.
105 hours on the new port and star engine and ignition system.
Seems like port engine is running out of fuel in bowl. Star engine is same configuration and runs fine.
I've replaced the carter fuel pump and swapped with the pump from star engine. No change.
Engine idles funny since this started last year. Thoughts?

Ayuh,..... Why not swap the carbs, motor to motor,.....

 

[beech2000]

Ayuh,..... Why not swap the carbs, motor to motor,.....

Thought about this too. I decided prior to to part swapping to actually listen to the knowledge on this forum and actually do the steps prior to swapping parts port to star.

A previous post asked a simple questions.
Did you check compression?
Did you check Fuel pressure?

Neither of which I could answer yes to.
So........ Now I can.

Compression Test all withing 6 PSI of each other and around 120.
Fuel Pressure test was a Total Fail "Zero" PSI on the port side.
So with the ignition on and fuel pump screaming, no fuel pressure. Looking like a bad anti-siphon valve or collapsed fuel lines.
Will dive in to it better this weekend. The Starboard engine fuel pressure is at 12PSI with ignition on.

 

[beech2000]

FUEL FILTER AND THE WATER FILTER . Q-JETS CARB
SO 105 HOURS FUEL FILTER !

Fuel separators checked and no water noted. Looking like a blocked anti-siphon valve.

 

[beech2000]

Normally a new motor would be solid, but if fuel system (carb in this case) is running lean it can warp valves and damage pistons

You could do a easier test with a vacuum gauge on the line coming from the fuel tank to the fuel filter. If you get less than 0.5 Hg then your good. More than that there is most likely a clogging in the fuel tank or antisiphon valve.

If no more than 0.5Hg then need to look at the pump to carb

Line by line, piece by piece verified .07"HG on vacuum gauge until I got to the water separator. Turns out on older fram water separator housing there is a 1/4" NPT anti-siphon valve. When I replaced that fitting with a straight 1/4" NPT nipple I'm getting fuel through lines.
I was also successful in plumbing in a fuel pressure gauge using a 5/8"-18 inverted flare to 1/4" NPT to gauge fitting. I'm now seeing about 6PSI at Carb inlet. I half filled an empty quart oil container in about 2 seconds of running the carter fuel pump. Strange thing is when I reinstalled the anti-siphon valve all is still good. Could I have had air lock the whole time?

 

[alldodge]

Strange thing is when I reinstalled the anti-siphon valve all is still good. Could I have had air lock the whole time?

Possible, but could also be the antisiphon valve was stuck and during the removal/reinstall it freed up

The 1/4 antisiphon valve is to small for the motor, need at least a 3/8

 

[Bondo]

Possible, but could also be the antisiphon valve was stuck and during the removal/reinstall it freed up

The 1/4 antisiphon valve is to small for the motor, need at least a 3/8

Ayuh,....... 'n there should only be one check-valve, at the tank's outlet,.....

 

[Scott Danforth]

anti-siphon fitting should be 1/4" npt to 3/8" hose

Could I have had air lock the whole time?

possibly

 

[beech2000]

Thanks to all for your replies. Using a vacuum gauge to determine fuel restrictions is brilliant.
I ran here on a plane today at 3800RPM. It's been awhile since I've been able to do this. Very much into the Q-jets vacuum secondaries. 15,000 pounds on a plane $$$

 

[ROY WILLIAMS]

Thanks to all for your replies. Using a vacuum gauge to determine fuel restrictions is brilliant.
I ran here on a plane today at 3800RPM. It's been a while since I've been able to do this. Very much into the Q-jets vacuum secondaries. 15,000 pounds on a plane $$$

The fuel gasoline Maintenace carb/filter/tank/water filter. 6-8 psi. fuel carb.

 

[bobyouruncle1]

Fixed?
Gas tank vent?

 

[beech2000]

Problem was and is a stuck anti siphon valve
It just did it again. Vent is clear. Which way does the ball end of the 1/4" npt anti siphon valve point to? Tank or carb
I think i installed it bakwards. I dont have the starboard engine floor up to cross check