Help with CRX, dies after it warms up

[splatterdog]

Removing the cap isn't really the fix, just a test for excessive vacuum in the tank, possibly from the evap system. I guess the cap could be at fault too. 4wdchico mentioned you had some evap situation previously.

I would still want to know how much fuel pressure is there when the problem is occuring.

[4wdchico]

Removing the cap isn't really the fix, just a test for excessive vacuum in the tank, possibly from the evap system. I guess the cap could be at fault too. 4wdchico mentioned you had some evap situation previously.

I would still want to know how much fuel pressure is there when the problem is occuring.

I second the fuel pressure issue. When faced with problems like this, I put a T fitting into the fuel line and run a long hose out the grill to a pressure gauge taped to the windshield and go for a drive.

[Petros]

okay, so what does the pressure gauge tell you? What are you supposed to see? If it is too high, how is that corrected.

You know it is funny you should mention that; when I was replacing the engine I pulled the fuel lines and the fuel wanted to dribble out of the main in coming line. I put a screw it in so the garage floor would not get covered in gasoline. I was thinking that the tank was allowing fuel to flow out the line, but it did not stop when I raised it up high, so I put the screw in it.

It did not occur to me that the tank is low in the back and should not have been bleeding fuel out line at upper firewall level. Could the high ambient temp in the now infamous Texas heat wave cause too much pressure build up in the fuel tank? what normally allows the fuel tank to vent to atmospheric pressures? If the heat is perhaps overpowering the float with too much fuel pressure in tank, how is that corrected?

[4wdchico]

The venting of an evap fuel system is usually partly done thru a one way valve in the filler cap. Air can be drawn in but not flow out. The tank vents to the atmosphere thru the carbon canister any time the pressure in the tank is higher than the ambient air pressure. The carbon canister will always have at least three openings: one going to the fuel tank, another going to the carb or throttle body, usually via a purge solenoid, and another that vents to the atmosphere, while this is happening, the hydrocarbons are stored in the carbon in the canister. When the engine is running, and all conditions are met, the purge solenoid opens (if so equipped) air is drawn into the carbon canister thru the atmosphere vent and purges the stored hydrocarbon vapors into the intake to be burned.

On the carbon canister in a t4wd the atmosphere vent is the line coming out the bottom of it that goes into the unibody frame rail.

Fuel pressure on a carbed car is usually in the 5-7 psi range. Less for a Weber equipped car. The fuel pump should have a built in fuel pressure regulator. While I have not seen it happen, I suppose that the internal FPR in the fuel pump could become clogged and the pressure could rise above specs.

[Petros]

The system in the CRX is very similar to that in the Tercel. So it appears if there is a pressure build-up in the fuel tank it would be caused by a blocked up carbon canister?

I swap fuel pumps at a test, since I had a spare, and the car acted the same with either pump. The problem is not likely the pump.

[splatterdog]

The pump may be OK, but it sounds like fuel starvation. If it runs with starting fluid, that pretty much confirms lack of fuel.

[Petros]

that is what I think. so what in the system would starve it from fuel only after it warms up? I am thinking to verify the fuel shut-off solenoid is suspect.

Could being too rich cause it to die, and the starter fluid allows it run when it is otherwise too rich?

[4wdchico]

A pinched/plugged tank to carbon canister line or clogged canister could cause the pressure build up you mention. I have only seen failing carbon canisters that are falling apart internally and loosing their carbon. But I have heard of them getting plugged up, usually by having raw gas flood them.

First, I would proceed as Splatterdog advised and drive the car w/o the filler cap. I hope the tank is not too full when this test is done. If no more problems w/o a filler cap, then I would put the cap back on and T into the fuel line just before the carb and drive it while watching a pressure/vac gauge taped to the windshield. All suspicions about pressure or vac in the tank should be revealed at that point.

[4wdchico]

that is what I think. so what in the system would starve it from fuel only after it warms up? I am thinking to verify the fuel shut-off solenoid is suspect.

Could being too rich cause it to die, and the starter fluid allows it run when it is otherwise too rich?

I'm also guessing that you are starving for fuel. Starting fluid can be used to help start a flooded car, but if it does fire, it quickly becomes very obvious that it was flooded as it clears out and you would know it for sure.

A fuel tank that is not properly vented, as in allowing air in to compensate for the fuel being consumed, may flow enough fuel for a while, long enough for the engine to warm up fully and then die. If that is the case, the fuel pressure will go to zero on a pressure/vac gauge if driven long enough (they used to be called fuel pump testers back in the day when fuel pumps also provided vac to run the hated vac powered windshield wiper motors).

[Petros]

I am thinking to get another carb here at home, rebuild it and check out all the componets (float level, fuel cut-off solenoid, auto choke, etc.) and just swaping it out when I get back to austin.

So what would you guys guess the chances are I can solve the problem by just swapping out the carb and everything on it? Or could it be a waste of time?

Should I also change the fuel filler cap too? Cheap test.

Is there a simple test for the charcoal cansiter? what is the fix if it fails?

[4wdchico]

I am thinking to get another carb here at home, rebuild it and check out all the componets (float level, fuel cut-off solenoid, auto choke, etc.) and just swaping it out when I get back to austin.

So what would you guys guess the chances are I can solve the problem by just swapping out the carb and everything on it? Or could it be a waste of time?

Should I also change the fuel filler cap too? Cheap test.

Is there a simple test for the charcoal cansiter? what is the fix if it fails?

If the fuel tank is not above half full, I would just have your daughter drive it w/o a filler cap, or with the cap loose, before you even show up and see if the problem still exists. One of the best lessons I was ever taught is to make sure that everything else is good before ripping into a carb. Besides, doing the filler cap test first and then the fuel pressure test, if needed, if will show/eliminate all fuel supply to the carb issues without any major gyrations on your part.

[Petros]

removing the gas cap made no difference, the car still died out after it warmed up. So it appears to be something else.

What else could it be? What changes in the fuel system after it warms up?

[ARCHINSTL]

Obviously a guess on my part, as I've never owned a Honda. I'm also sure you've considered it, but - does it have a TVSV or similar like our cars?
Is there some sort of link from a heating sensor to the carb - as in a fuel cutoff switch?
Does it have an electric fuel pump that works "just so long" until it warms up? Not too related, I know, but a friend had a BritMobile years ago with an external electric pump that did this - not an SU, but can't recall the brand.
I think you mentioned before about joining a CRX Club for info on this - any help there - or just ricer news?
Tom M.

[Petros]

It has similar emissions system as the Tercel, it has three (or possibly more) TVSV type valves (each controls one function, unlike the Toyota TVSV). We have checked several of them (change one) with no luck. The CRX list people have not suggested anything different from the good folk here. It has a fuel cut-off solenoid which I am thinking of swapping out. I have a whole extra carb I was going to rebuild and just swap out (does not take too long to swap, and it will eliminate a number of possible causes, including the fuel cut-off solenoid).

Just looking for ideas to test after I get back to Austin (when it cools off!).