No power/"starving" T2

[nosfera2]

Hello all,

I have a 1973 1700 (CA engine code) auto van with stock carbs. There is supposed to be good compression on all 4 cylinders according to the garage.

I have the following symptoms:
No power, foot flat on the floor I (eventually) get to 40 on a flat stretch of road. This is where the fun begins, the van jerks/shudders, almost like there is an interruption in the petrol flow. The speed drops and continues dropping until I take my foot off the petrol. It will then start speeding up again once pressure is applied to the pedal. Till I get to 40 and then it begins all over again. It did the same thing going up hill at about 25.

I have eliminated the following:
It does this with the petrol cap on and locked, the petrol cap on and unlocked and no petrol cap at all. Up hill and downhill makes no difference.

I have been advised to check the pushrod length, just wondering if anyone else has any ideas.

[Piledriver]

A $5 fuel pressure gauge will tell you a lot...

Any history of recent work done that might have caused the problem?
Clogged filter? Van sitting awhile? Bad gas?

I got some crud gas once that coated my plugs with varnish, similar symptoms, only a new set of plugs fixed it, cleaning did not work.

[nosfera2]

A $5 fuel pressure gauge will tell you a lot...

Good point, will see if I can find one tomorrow to test with. I believe 3.5psi is the correct pressure?

Any history of recent work done that might have caused the problem?
Clogged filter? Van sitting awhile? Bad gas?

I have a fuel filter I am going to replace. I have had work done recently, but this has been an ongoing problem.

I got some crud gas once that coated my plugs with varnish, similar symptoms, only a new set of plugs fixed it, cleaning did not work.

I was planning to pull the plugs to see if there was anything I can see on them, although the garage said the plugs were good. But maybe I should replace them any way.

[dstar]

Eh, 2.5 - 3.5 should work.

In YOUR case, it sounds like a VOLUME problem, not pressure....

When you take the gasl line off of the filter, notice how quickly it flows
out of the line.

It should FLOOD out of there if the pickup and lines are clear.

Good luck!

Don

[nosfera2]

Eh, 2.5 - 3.5 should work.

Think I got the 3.5 stuck in me head - am planning to put Dells in my bus (another post heading to STF real soon)

In YOUR case, it sounds like a VOLUME problem, not pressure....

When you take the gasl line off of the filter, notice how quickly it flows
out of the line.

It should FLOOD out of there if the pickup and lines are clear.

Good luck!

Don

OK cool, will look at how it flows out when I pull it. Will report back tomorrow. I do know when I put the fuel filter in it had a thicker pipe to the gas tank side and thinner to the engine side. Not sure why.

[dstar]

Yes, the filter has two sizes of pipes also.
9mm and 7mm? Sounds about right.....

In the end, the carbs might have to be removed and cleaned to
fix this....

Don

[Piledriver]

If memory serves me right it should be ~ 1 liter/min at idle.

[nosfera2]

Yes, the filter has two sizes of pipes also.
9mm and 7mm? Sounds about right.....

That does ring a bell 9mm and 7mm

In the end, the carbs might have to be removed and cleaned to
fix this....

Don

I was thinking along those lines too. But figured I would exhaust other possibilities first. I would hate to replace the solex carbs with the dells and still have the same problem.

[nosfera2]

If memory serves me right it should be ~ 1 liter/min at idle.

Thanks, that gives me something to work with. I can't seem to find a cheap fuel gauge. The question is (being a bit of a newbie)... how would I test that? Where could I pull a pipe and still have the engine idle? One side of the T piece that supplies the 2 carbs? Sounds a bit explosive to me. All suggestions welcome!

[dstar]

Exactly! If the fuel doesn't seem to run very quickly,
blow air into the line. Yes, take the cap off, no don't do it with your
mouth.....unless you LIKE the taste of gasoline and the increased
risk of oral and esophagal cancer....


Don

[nosfera2]

Exactly! If the fuel doesn't seem to run very quickly,
blow air into the line. Yes, take the cap off, no don't do it with your
mouth.....unless you LIKE the taste of gasoline and the increased
risk of oral and esophagal cancer....


Don

Erm, no, don't like the taste....
OK, so I'll disconnect at the bottom of the T piece (ie the single line coming from the tank to the carbs) and see what kind of flow I get? And if it is lousy put a bast of air in from the fuel tank cap side of things?

[Piledriver]

You may have rust/crud blocking the pickup, take the gas cap off and blow BACK into the tank.

Did I mention take the cap off the tank? Hint Hint...
(Unless you want to wear it)

If that fixes it, you might want to pull the pickup and maybe pull the tank... (requires pulling the motor unless you have a pickup)

[nosfera2]

You may have rust/crud blocking the pickup, take the gas cap off and blow BACK into the tank.

Ahhh, the light bulb goes on, OK gotcha.

Did I mention take the cap off the tank? Hint Hint...
(Unless you want to wear it)

...And this Winters new look is 97 petrol sprayed all over the place, with a disgusting taste in the mouth... Hint taken

If that fixes it, you might want to pull the pickup and maybe pull the tank... (requires pulling the motor unless you have a pickup)

Hopefully no engine pulling required. Will give this all a go first thing in the morning.

[nosfera2]

Yesterday, nice sunny day, spent it under the van, cosying up to my fuel pump.

The flow from the tank seemed good, ie gushing out. Checked the flow through the filter I put in, that looked good too in a gushing kind of way.

Having no compressed air and contrary to the advice I was given on here, I blew into the pipe leading from the tank (as per dstar/piledriver) sans petrol cap (I apply what I can ). I blew real hard and heard bubbling from the tank.

Next was the fuel pump. I have a spare engine I am planning to rebuild so pulled the pump off there. It was a Brazilian one. Popped that on and all seemed OK until I took her for a test drive this morning. Very bad.

Take the old pump to pieces, but not totally as I have no rebuild kit. Did the blowing back into the tank again. Replaced some sections of fuel pipe, put the old pump back on again.

She seems a lot better driving here up and down my road. Going to venture further in a moments time. So am not sure what it was. Once I have rebuilt the other engine and I am swapping it all I will probably pull the tank too and have a look.

Thanks for all the assitance chaps, much obliged.

[nosfera2]

OK, so after a test drive, am still pretty much in the same place, however have found the following:
It happens when my foot is flat on the floor and the engine is under load ie pushing the bus forward.

Does that sound like too much or too little fuel getting through? I guess the only way to test would be a pressure gauge?

If I keep my foot flat the engine keeps spluttering and coughing, with pops every now and then. Until I take my foot off. Rev once or twice and away we go.

If I rev it a bit it seems OK. I could not test with the engine not under load ie foot to the floor and the van not moving for an extended period of time. Will need to find a deserted parking lot before I can do that.

Anymore suggestions gentleman?