To Vapor lock or not to, that is the question....Electric fuel pump?

[Rickf1985]

What you can do is disconnect the fuel line before all of the pumps and run it out of gas so the carb is empty. Then hook the line back up to the pump and while you are watching the gauge have someone turn it on and watch the pressure as it fills the carb up. In your case that is about as real world as you can get short of running a gauge wire all the way to the front. You will not have long to see what the pressure is since it should fill the carb in seconds. If it takes longer than that then you have flow issues. If that is the case considering all you have done I would check the carb for float drop, inlet needle size and any restriction in the needle and seat area. Could be a piece of rubber from an old line stuck in the entrance to the needle.

[legomybago]

I've got the carb on the bench, going to work on it today hopefully

[Rickf1985]

Simple solution.......................... 5.9 Cummins. W%

[legomybago]

Here's what I found with the TQ:
Everything looks great! Except for my float bowl adjustment from a couple years ago....I bent the "tang" that touches/closes the needle in order to set the correct 1" float height. Doing some homework today, a Thermoquads floats are adjusted by bending the float arm itself. I didn't know that. SO....now I need to figure out the correct position of the needle shut off metal tang,  then adjust the float height. Reading info online hasn't quite answered this question completely...some say the float should almost touch the air horn body (in the closed position),then adjust the float? But when the float assembly is down to where it almost touches the body, it puts the needle/float tang at a crazy angle? It still shuts off fuel flow, but looks like its pushing the needle to the side vs straight in on it? Is this making any sense to anyone? Lol.  I'm not seeing much info on "needle drop" specs with the TQ

[Rickf1985]

It has been a LONG time since I worked on a TQ but if I remember correctly when the float is sitting on the table the tang will be at about a 30 degree angle. you do want it pushing pretty much straight at the needle. Worse comes to worse you can probably still buy just a new float.

[legomybago]

Yes Rick, a friend recommended I replace my plastic floats with brass also. On the web they are about 25 bucks. I'm going to double and triple check my float height/position and current needle drop/full open measurements before I order. I love just throwing money at the beast. I have two fuel systems now? Which do I run if new floats fixes? So many decisions.....and wasted time. I have a FMC club camping trip I'm trying to make by the end of the month....There's going to be 9 other FMC's, Id sure like to see other ones besides mine. Who knows... i??

[legomybago]

It has been a LONG time since I worked on a TQ but if I remember correctly when the float is sitting on the table the tang will be at about a 30 degree angle. you do want it pushing pretty much straight at the needle. Worse comes to worse you can probably still buy just a new float.

When I adjusted the tang to meet the needle straight on, it puts my float extremely low into the bowl when in the closed position, to where I would have to bend the float upwards to get my 1" height. All the information I've read/learned about Thermoquads float system, show adjustments being made bending the float downward to get the correct height, not upward? Like the floats should be up almost touching the air horn/gasket when closed? I'm probably going to modify my floats first before buying others and give it a shot. I miss Holley external float adjustments....lol

[Rickf1985]

It is possible these floats were adjusted before plus the adjustments you made will change everything so you are starting from scratch. But starting with the needle being pushed straight is a good place to start. Do a google search for "Carter Thermoquad float" and look at the pictures that come up and you will get a good idea of where they should be. Get as close as you can.

[BrianB]

I've never owned a Dodge (and never will), but does this guide help you any? http://www.autozone.com/repairinfo/repairguide/repairGuideContent.jsp?pageId=0900c1528007fc3f

[legomybago]

It is possible these floats were adjusted before plus the adjustments you made will change everything so you are starting from scratch. But starting with the needle being pushed straight is a good place to start. Do a google search for "Carter Thermoquad float" and look at the pictures that come up and you will get a good idea of where they should be. Get as close as you can.

That's exactly what Im going to do.....

That's a good link for diagrams and measurements for the TQ too Brian.

[legomybago]

I found a needle that was sticking in the closed position way to easily, was grooved, after cleaning the needle tip off best i could, it still wants to be sticky....So I just ordered brass floats and a new needle/seat.

[Rickf1985]

I think you may have found your problem. That would suck after spending so much time and money on the rest of the fuel system! At least you have a good supply of fuel pumps on hand. W%

[legomybago]

I think you may have found your problem. That would suck after spending so much time and money on the rest of the fuel system! At least you have a good supply of fuel pumps on hand. W%

YES!! Your reading my mind Rick! NOW I will have to choose which system to run? Electric or Manual.... Hm? I'm pretty sure I will leave the electric pump mounted in place, and have it for back up if ever needed, but by-pass it and just go back to the mechanical system. I never pulled the mechanical pump off, just by-passed it to run the electric pump, so easy peesy. All the FMC owners I've talked with say they never have vapor lock issues with the short length fuel system and design etc...You even thought that too Rick. I hope my fix works....just waiting on shipping now.

[legomybago]

[/size]I put the new brass floats in and have smooth working needles.....BUT same issues. Pulls hard until 40 mph or so, then starts falling on its face. Brought her home and pulled the tank pick-up out, I thought maybe I'd see a pin hole or something up high, but no, looks to be in excellent condition. I think I need a new carburetor. I'm out of trouble shooting options as far as I'm concerned....[/size][/font]

[Rickf1985]

I am beginning to wonder if there is not something mechanical in the engine? Cam timing or cam worn? Have you checked fuel pressure while this is actually happening? That is the only way to determine the fuel system condition.

[legomybago]

FIXED!!!! I tapped in a fuel pressure gauge with clear tubing, taped the gauge to outside rear window, as I drove the rig my helper watched the gauge. Under hard acceleration, the pressure would drop to zero followed by air bubbles! We then started by passing the supply line. WAM!! It was the fuel filter assembly introducing AIR into the system before the fuel pump. It ran great down the highway maintaining 6 psi with no bubbles. Talk about throwing me for a loop   I was ready to give up for awhile on this one. Thank you Rick for sticking this one out with me. And everyone else too...Seriously. I will post a couple pics tomorrow of the gauge set up

[legomybago]

Heres the clear tubing and fuel pressure gauge tapped into the system post pump.

[legomybago]

This issue really through me for a loop, I knew it was fuel related, but I kept focusing on the wrong end of fuel pump (as described in lengthy detail in this thread). I've only had this issue one other time, years ago, and it was on a 1986 Ford diesel truck, and we found the air using clear tubing also. Something to keep in mind folks....AND if you do have an air leak pre pump, doesn't mean you will EVER see a leak when the engine is not running.... W% I thought I should have seen some fuel seepage somewhere....NOT

[Rickf1985]

I thought I said something about pulling air several pages ago. The main thing is that it is fixed and you have LOTS of leftover parts now. You should NEVER have a fuel issue again.

[legomybago]

I actually only lost about a 125 bucks and 14 days off the end of my life on this one....2 fuel pumps, a couple misc carb parts, fuel line. Could of been worse...

[DaveVA78Chieftain]

In case you might need some reference info in the future: Daves Thermoquad Page

[Rickf1985]

DAMN! I will never try to give advice on a Thermoquad again! Just pass that link on.

[DaveVA78Chieftain]

LOL Rick.  Born from fighting the same problem he had.  I still have the problem.  Will be trying out his suggestion when I get my Winne back on the road.  I am currently tied up rebuilding the Isuzu 3.2L V6 in my Rodeo that spun number 1 rod bearing.  I simply cannot believe Isuzu said 1 quart in 1000 miles is acceptable when the problem was not enough drain holes in the piston oil rings.  I just did not know about that little bit of info.  OK, back to carburation and fuel delivery.  Dave

[legomybago]

Yes Dave, I've gone through your info many times, such a wealth of info for everyone, very much appreciated.
I tell you what people...If you think you are having issues with running out of fuel under a hard load, tap in a piece of clear tubing with a fuel pressure gauge at your carb and take it for a drive and see what's going on. You can then by pass fuel lines and filters pre pump and find your problem. Hell of a lot easier with a front engine rig, one person can trouble shoot it driving down the road.
I was ready to park the FMC and take a break from it...I figured it was just going to need a new carburetor, even though I couldn't find any other problems with the TQ after I just had it out and apart??.....Imagine how pissed you would be after spending 400 dollars on a carb, just to have the same issue!!!!!!!!! An issue that's FREE!!!!!!

I too have the same Rodeo with the 3.2. Uses a quart of oil between oil changes. When I first met my girlfriend six years ago, the car was using 2-3 quarts between oil changes!! I did my homework, and like you said Dave, Isuzu has bad oil relief holes in the pistons, and they got around it without any recalls past 36k miles. I changed to 10w-30 standard dino, and I also cleaned out the EGR intake tube that runs inside the intake manifold, They clog up with suit/carbon. You can email/message me if you need some more details on cleaning that tube Dave. We have 180k on the clock, and it's actually going up for sale this week, we bought a newer car. Ok back on track OZ

[DaveVA78Chieftain]

I also cleaned out the EGR intake tube that runs inside the intake manifold, They clog up with suit/carbon.

I have the engine out of the car and tore down in my garage.  Top & bottom halves of Combined Chamber (inside and Outside) are all clean and shiny now.