Engine bogging

[keepviper13]

I've read through a few of the other "engine bogging" threads and haven't been able to come up with a solution for mine yet.
Starts up fine, will idle fine, even revs like there's nothing wrong.

Go to head down the road though and any time you are trying to "cruise" the engine will just bog down.
It won't maintain any speed of any sort without falling on it's face.

I did find that if I continuously pump the gas pedal it will "keep up" and not bog down but somethings not right.


Any thoughts?

[Buzz]

Fuel pump or fuel filter. A good friend of mine, who had been a mechanic at one point in his life, says to start with the simple explanation first. After spending a lot of time on my own theories, I have learned my lesson.
In your case, my thinking is this, it was ok at idle but not at speed. What is needed at higher speed? More fuel or more air. Sark at lower speed should be fine at high speed unless the timing is off.
Let us know what you find.

[Buzz]

I meant "spark" at low speed.... My typing on an iPad is not so good.

[krick3tt]

Similar issue... new plugs, adjust carbs, timing, new fuel filter. Much better.

[4x4Pinz]

check them carbs to be sure they are tight. holding the linkage down will move the carb bodies and pumping will allow the air fuel mixture to return to a more normal state even for just a short bit. Yes you do need to take the air plenum off to make sure the carbs are tight.

[keepviper13]

Carbs are tight.
Air filter didn't look bad but I believe it's fairly old since it's a FRAM CA3015 which apparently doesn't exist any longer.
Ordered a new one for it.

That being said the fuel filter was pretty gummed up. (even though it's only been on there 6 months)
Picked up a new one and we'll see if that was the issue once everything else is back together.

[undysworld]

You might want to search for "red death", as some call it. The lining of the tank can delaminate and go into the fuel lines. It can be repaired. It hasn't happened to me, so I can't offer advice.

[keepviper13]

You might want to search for "red death", as some call it. The lining of the tank can delaminate and go into the fuel lines. It can be repaired. It hasn't happened to me, so I can't offer advice.

There were a few flakes of the coating, but hopefully that was just from being stirred up from the tank being dropped not long ago.

[keepviper13]

That was easier than I had anticipated.
Got it all back together and it runs great again.

New fuel filter is all that it took.

[murrayjp]

I have a similar problem, yesterday on the way home my 712 started to bogged down when I left the traffic light to point it die. History yesterday it was around 95 degrees and very humid. I was coming back home no problems until I got into traffic and whenI went to start moving it would bogg down to point of a turtle pace. well it die in the intersection wouldn't start. after letting sit for twenty minutes it stared I was able to get home. It was hard to start after driving it a while.

I am thinking. vapor lock in the fuel system due to lovely heat in Fla 95 degrees
maybe a lose fuel pump or dirty fuel filter ( a friend told me to check those first)

should I insulate the fuel lines, maybe add eld fuel pump

thank you
Bill
N.Fla

[rmel]

Not likely vapor lock, 95 is not all that hot and your at Sea level.
Vapor lock is more prevalent at high altitudes AND hot. At Alt
vapor pressure drops.

If you go the route of an electric fuel pump don't mount it in the
engine compartment, mount it as close to the bottom of the tank
as possible -- even for siphoning diaphragm type pumps such as a
Hardi. It gets pretty hot near the base of the mechanical fuel
pump -- over 160 degrees.

[boeing7873]

Original fuel pumps work great. If changing a working mechanical pump for an electric pump solves your problem, you are actually only disguising it. The Austrian engineers did it right. Going electric is a poor option, non-elegant, complicated, expensive, probably more dangerous, and will prevent you from finding the real problem.
(Of course, please forgive me if you are going electric for the purpose modifying the engine outside of original specifications, such as installing a EFI system, or different carburators.

Vacuum leaks are very common and easy to detect. Make yourself a smoke machine (watch youtube videos) and smoke your intake and carbs from the brake vaccum hose. You will be surprised. Look carefully with a good light, all around your carbs, and inside the wind tunnel.

[pinzinator]

I have used a Facet electric fuel pump for about 7 years on my 710M. Never had a problem of any kind, and I have driven it at temperatures of 115 degrees. The engine starts easier when cold because the pump fills the carb bowls before cranking. I have the pump mounted on the engine right where the old mechanical one was, but an option is to mount it on the body or frame so it isn't subjected to vibration. I would never go back to a mechanical pump except in an emergency.

The Facet part number is 480564. The 24 volt feed is connected to the fuel solenoid harness. I have a Holley pressure regulator installed between the pump and carbs, but I don't think it is necessary as I had to adjust it all the way out to get the correct pressure. I left the regulator in place because it has 2 outlets, which allows an individual fuel line to each carb.

The PinzSSI 3.0 version is shown also.

IMG_2986.JPG (591.59 KiB) Viewed 8043 times

[pinzinator]

I did some verification tests on the fuel system today and discovered that the recommended pump puts out about 4.3 PSI unregulated. I dialed it back to 3.3 PSI, which took all of 2 minutes using a 16mm box end wrench and a 5.5 Allen. Here are photos-

IMG_3020.JPG (499.88 KiB) Viewed 7929 times

IMG_3019.JPG (475.34 KiB) Viewed 7929 times