Help with CRX, dies after it warms up

[Petros]

Hi all,

I thought I would post the new problem we have with my aught's crx to see if anyone has any ideas.

As most of you know my daughter has an '86 CRX DX (carburetor) and I recently swapped in a complete rebuilt long block. I swapped over all the external parts, and now have a drivability problem after it warms up.

The engine starts and runs great, it can be driven for a few blocks, quiet and strong. But after it reaches operating temperature it refuses to stay running. Acts like it has no fuel because I can get it to run briefly if I spray starting fluid down the carb. I see no visible problems wit all the hoses and parts, the carb is getting fuel. I double check the valve timing and the spark timing, it has fuel in the carb because I can see it squirt down the barrel when I advance the throttle by hand.

I suspect it has to do with the emission control system, one of the many devices on the fuel system that changes when it reaches operationg temperature. It has a fuel cut off solenoid just like the Tercel, so I suspicious of that (or the sensors it runs off of). Does anyone know if there is something else that will stop it from running that is temperature dependent?

During the engine swap I found a few vacuum leaks in that Gordian's knot of vacuum lines and fix them.

I really need to get this car running reliably.

Thanks for any ideas.

[4wdchico]

Providing that you can not find an issue with the fuel cut solenoid/system I'd make sure that any TVSV's or vac solenoids that are involved are switching correctly when the engine fully warms up. If the TVSV's/vac soleniods check out ok, then looking further at the vac systems that have vac applied to them when the engine is hot would be in order. If no luck there, I'd look at the vac systems that are switched to a no vac situation when the engine is up to temp.

I ran a few searches on RA, AZ and Google for TVSV's and VSV's for the CRX and nothing came up. I did find references online to an EGR solenoid and a start control solenoid and this seems to confirm my suspicions that you are dealing with a computer that controls the vac system via vac solenoids. Hybrid systems were somewhat common in the mid '80's, my '86 Bronco with a FI 5.0 V8 has a hybrid vac setup. The instructor at the CA smog course specifically cautioned us about the horrors of dealing with that era of Honda cars. I have been lucky and only have messed with the FI versions. Hope you have a DVOM handy.

There is a chance that the vac leaks you fixed were allowing the car to run ok with an underlying vac system problem. I'd be hoping to find a partially cracked plastic vac nipple on a vac solenoid after an engine change.

The real problem is that the better that you get at fixing anything, the more bizarre and challenging problems are thrown at you. So you might consider this issue you are currently jousting with a back handed compliment of sorts...

Feel free to call me is need be.

[Petros]

There are like 5 or more TVSV type devices, one was cracked (I put sealant on it) and I thougth that was the problem. I sent her a replacement and she and a friend got it in, no luck. All of these devices are located on the underside of the intake manifold and a real PIA to get at (easiest way to jack the car up and get to it from under it!).

The fixed vac leaks creating the problem occurred to me too. It kind of acted a bit odd at low rpm before I replaced the engine (before the overheating that prompted the new long block). It ran rough and occasionally stalling out. Like a vac leak. I found and fixed three vac lines, and also sealed the large rubber carb mount (a common source of vac leak as these cars age, confirmed with carb spray it was leaking vac under the carb). If it was running too rich, the vac leak would make it run more or less normal. Or if what ever is faulty allows less fuel or more air, the vac leak would also allow it run. It would be an interesting experiment, create a large vac leak and see if it will stay running. But it may not help me find what is wrong.

This particular model was likely one of the most complex carb systems ever on a production car (after this model they went to all EFI, with much better fuel control and a lot fewer components). It has about 3 to 4 times the vac lines as our Tercels, they all go into and out of a number of large plastic boxes that have electrical connections going into them. Something switch and on and off these vac lines, and whatever they go to, during different driving conditions. I would hate to have to check all of them, it seems I should be able to narrow it down to a few that might cause this kind of behavior.

[4wdchico]

When faced with this kind of issue, nothing helps like prior experience. If you could find a former Honda line tech in your daughter's area who dealt with these cars back in the day it might be worth spending some coin for their expertise. I have had good results in finding the correct technician by making inquiries at the local NAPA and Carquest parts houses, those guys really know who the good mechanics are.

I have had no luck in getting good info on the engine in that car. It is a CVCC engine with a three barrel carb , right? If so no Weber swaps.

[ARCHINSTL]

This is really a "no help" message (albeit a commiseration).
Ny '88 Dodge Ram 50, AKA Mitsubishi Mity Max, has an inordinate number of vac lines, vac lines going into boxes, vac lines going into plastic valves compared to our Tercs. Mitsu used these similar systems for at least a few years prior to my '88 and presumably used it until EFI was introduced. This 2.6 (and 2.0) Silent Shaft engine was also used on a number of Mitsu and Chrysler cars of the era, so I guess its Medusa Mess was used on them as well.

Was this peculiar to the '80s Mitsu and Honda motors for the reason that they were dirtier and harder to control than the equivalent Toy motors with carbs?

I may be coming to a point where I have to make a decision to get a Weber for the Mitsu or junk the p'up because of the cost of the Weber and putting it on a truck whose chassis is Swiss cheese. Incidentally, the mystery noise and high, unresolvable, idle of some months ago that I mentioned in this truck has literally disappeared. Why? Who knows...
Tom M.

[Petros]

yup 4wdChico, the three barrel carb with the stratified charge combustion chamber. CVCC "controlled vortex combustion chamber". The small combustion chamber has a rich fuel air mixture, and the large one has a very lean mixture. An earlier vershion of this car was the last car that did not need a catalytic converter because it was so much cleaner than the all other carburetor engines. But increased regulations to clean up the exhaust even further finally was the end of all carburetors in cars, including the Honda.

So honda has two or three of everything that the Tercel has, one for each barrel of the carb. Only one fuel cut off solenoid however. So I will have to look into that when I get back to Texas.

I have two service manuals for this car, one is in Texas. Neither of them cover the whole emission systems completely in detail. I am with you on finding expertise, but I do not know where to look.

[4wdchico]

One other thing to think about: a number of vehicles from that era gave waaay to much weight to the reading of the coolant temp sensor that is connected to the computer. In other words, a coolant temp sensor that is a bit off can make such a vehicle go much farther of calibration than you might think.

So, if you are really lucky, the problem could be as simple as a bad connection to the ECT sensor.

[rer233]

egr maybe? (tho i'm sure you've already been there if the honda even HAS egr.) just a thought... good luck!

[Petros]

Yes, it has EGR. I did not think that would cause it not to run, would it? Everything externally seems normal with the system, but I have not done any tests on it.

Temper sensor: good thought, I have two spares. The wire connector came off the end of the old brittle wire and I had spliced a new one on with the crimp type connector. This usually works okay but it is worth a look. Does that prevent the engine from running? Seems to me that it should have a default run mod if it goes bad or if the connection is lost. Easy check any way.

[splatterdog]

If the egr is coming on at idle it will cause a stumble/stall. It would likely take misrouted vacuum hoses to have that happen though. An 80's Honda could certainly have that happen with their spaghetti. Unless of course the hoses are all nicely heat/age molded in place.

Not sure if a CTS would affect a carb engine that much. Some cars, Saturns in particular, freak out when their sensor/connector go bad.

Just about everything here has been covered so far except, what about the idle setting? Maybe as the choke relaxes and it comes off the high idle cam, the base idle might be too low.

Gotta love 80's carb systems...

[Petros]

just to make sure about idle setting I screwed in the idle setting several turns. No luck.

When it is hot out (normal in TX this time of year, even without setting records), after it was fully warm, it would not even stay running with throttle all the way to the floor. Would only run briefly with starter spray down the air cleaner, but could not keep it running even with throttle to the floor. Let it cool down all the way, starts and runs great, can drive it around the block. As it reaches operating temp, it stall out at low rpm, and than it will not stay running at any rpm.

It will have fuel in the carb (squirts fuel down the carb when throttle advanced). Swaped fuel pump and fuel filter just to make sure, no luck. I did not check if there was spark after warm up, though it seems there should be since it would start and run with starting fluid (indicated it is likely fuel starvation problem).

I am tending toward fuel cut-off solenoid, or what ever sensors control it.

[splatterdog]

The fuel cut solenoid is likely not sensor controlled but ignition switch fed. It's main function is to prevent run on when the key is turned off. I don't think that's the problem though. Even if the solenoid was shut, it wouldn't prevent wide open running.

Kinda sounds like vapor lock. When you look for accelerator pump squirts, how many times do you pump it? The bowl can run dry but the accel pump typically has it's own small reservoir. If it runs dry after a few strokes, then you have a supply issue.

No sight glass? Are there any harbor freights nearby? They have cheap combination pressure/vac gauges for carbs.

[4wdchico]

Hmm, what Splatterdog said about vapor lock got me thinking. I do recall you having to do something with the evap plumbing on that car, correct? Did you check for a build up of vacuum in the fuel tank right after it is run enough to warm up and stall out?

[splatterdog]

Hmm, what Splatterdog said about vapor lock got me thinking. I do recall you having to do something with the evap plumbing on that car, correct? Did you check for a build up of vacuum in the fuel tank right after it is run enough to warm up and stall out?

Good point. Remove the filler cap and see if the problem goes away.

[Petros]

You mean all it could need is a new filler cap? I did replace it several years ago with another used cap I had, it would burp fuel out the filler cap before (but it still ran okay). The used replacement cap can be bad. Worth a try anyway.

When i replaced the cap I put in another evap canister and plumbing from the parts car. This was about 2 years ago and has not been an issue since.

I pumped the throttle a number of times and got fuel on each. There is a sight glass on the carb but ti is almost useless, it is buried under a lot of vac lines and you can not even line up your eye to get a good look at it. I did not bother to check it since it had fuel. but it could have been flooding too.