[85MR2RED]

I recently acquired a 85 MR2 MK1 that had been sitting in southern CA for the last 10-14 years. The car overall is in awesome shape and was well cared for generally. I have set about trying to get it back on the road. Let me continue by saying that I am not at all new to cars, I have been wrenching and building them since I was pretty young and I have a complete shop, however I have learned that when you don't know something to research and ask those who do.

I removed the tank and replaced the fuel pump and sending unit which were both toast. I reinstalled the tank yesterday and put new fuel in it. The car will start but then pretty quickly die. At first it would die very fast getting to probably not more than 500 rpm and now it will get to about 1500 and then die. It will do this twice after which it will crank but not fire at all. If I let it sit for perhaps 3-5 minutes it will do it again (start, rev to 1500 and die twice).

I installed new NGK plugs gapped at .44, checked all of the connections and I have new battery in it. I am now somewhat at a loss. I do have a manual (actual service manual) and I have looked at that and the only thing I can arrive at is perhaps the cold start injector or maybe the feed line is blocked (although it is getting fuel, I checked by cracking the return line). I have looked for any large vacuum leaks and anything obvious but have not been successful.

Any suggestions would be appreciated.

 

[salineselin]

It's worth changing out the fuel filter in a car this old simply as preventative maintenance. I'd more rightly suspect inconsistent or weak spark over fuel delivery though. If you have a timing light, I'd put it over each spark plug wire and see how consistent the flashing from the timing light is to validate spark consistency and delivery.

 

[85MR2RED]

Thanks, I should have mentioned that I replaced the fuel filter as well.

I will give that a try. It would seem to me that if it were a spark issue it would not start at all. Its starting and then dying which in my mind would be either poor or inadequate fuel pressure, a very large vacuum leak or a malfunctioning sensor.

Fuel pressure could be an issue as I do not believe I checked the high pressure line (I did clear out the return line). I need to test the fuel pressure to make a determination but I need to order a banjo fitting adapter for my fuel pressure gauge in order to do that.

While I could be wrong, I do not think there is a massive vacuum leak, I have inspected all of the vacuum lines and have not found any breaks or even cracks.

The sensor issue is a definite possibility but I just do not know this engine/system well enough to be sure. The car has the stock AFM on it and I have read that these can be a problem. I have also read where people have removed them but I am not sure how this is accomplished without ECU issues (or if it even creates an issue).

 

[85MR2RED]

This forum does not seem to be overly active, is there another MR2 forum that is?

 

[Winks42]

This forum does not seem to be overly active, is there another MR2 forum that is?

No not really, you have a 37 year old car.

Guessing you are only running on your cold start injector, as it starts then stops.

Check that your injectors are being powerd. first confirm you are getting voltage by switch the key to the on position and using a multimeter on the + end of the injector plug and the - end of the multimeter on the intake manifold. You should see 12v. Then I would clean off the ground which is located on the intake manifold, near the #2 cylinder injector on the intake manifold.

Your 85 also has a ballast resistor for the injectors,that might be the source if you are not getting power to your injector., it is located right behind the battery

Your injectors could also not be functioning for sitting for so long, you can check by using a 9v battery and jumping the injector and hearing for it to click

 

[salineselin]

I will give that a try. It would seem to me that if it were a spark issue it would not start at all. Its starting and then dying which in my mind would be either poor or inadequate fuel pressure, a very large vacuum leak or a malfunctioning sensor.

I thought the same thing when I was troubleshooting a hard start on my 87 mr2. The problem for me ended up being that the spark plug wire going from the igniter to the distributor was plugged in the opposite way. One connector was longer than the other, and this led to a gap between the distributor and igniter that would only bridge sometimes.

 

[85MR2RED]

I really do appreciate all of the responses. I know forums can be somewhat problematic given no one knows anyone else for the most part.

I do realize the car is 37 but I figured they still have a good following. I worked on late 60's and 70's cars all the time so I am familiar with ancient technology issues.

I did some testing today and determined that the pump is running, the line does have some pressure at least. The pump runs when trying to start so thats a positive. I removed the distributor cap and rotor and cleaned them, checked and cleaned all of the contacts. I tested the AFM IN accordance with the manual and discovered it is bad so I ordered another one.

I have little doubt that the injectors probably need some love but one thing at a time. I am hoping that the new AFM will make a difference.

 

[rmeller]

... I tested the AFM IN accordance with the manual and discovered it is bad...

How did it fail? Remember that we can't look over your shoulder.

You should try bypassing the crash interlock on the fuel pump. Put a jumper from B+ to Fp in the test connector, and see if that allows the engine to run longer. The AFM is part of the crash interlock, but we can't tell if that is what is going on here without the test results.

 

[85MR2RED]

I conducted the tests in the manual both the "on-vehicle" and the "inspection".

The on-vehicle test yielded the following results

Vs-E2 = 159 measured (20-3000 is acceptable)
Vc-E2 = 182 measured (100-300 acceptable)
Va-E2 = 282 measured (200-400 acceptable)
THA- E2 = infinity measured (various measurements acceptable dependent on temp but infinity is not acceptable)
Fc-E1 = infinity measured (infinity required)

The off car inspection tests yielded the following

Fc-E1 = infinity measures (infinity required) fully closed
Fc-E1 = 2 measured (zero required) other than closed position (I actually got a varying degree of readings here)
Vs-E2 = 166 measured (20-400 required) fully closed
Vs-E1 = 200-900 measured (20-3000 required) fully closed to fully open position

So the one in red is really the only one that didn't measure out within tolerance. I repeated all of these several times and got a wide variety of results.

 

[85MR2RED]

How did it fail? Remember that we can't look over your shoulder.

You should try bypassing the crash interlock on the fuel pump. Put a jumper from B+ to Fp in the test connector, and see if that allows the engine to run longer. The AFM is part of the crash interlock, but we can't tell if that is what is going on here without the test results.

I will attempt this today.

 

[rmeller]

THA- E2 = infinity measured (various measurements acceptable dependent on temp but infinity is not acceptable)

Fc-E1 = 2 measured (zero required) other than closed position (I actually got a varying degree of readings here)

This is the intake air temperature. This should have caused a CEL and a stored fault code. You didn't say anything about reading the fault codes, but if not, you should do that. Don't know if this could cause the engine not to start, but if there was in fact a CEL and fault code, then the ECU should have ignored this signal and substituted a default value that would allow operation.

This contact set does operate the fuel pump interlock. You don't state measurement units, but if it is 2 ohms, that should have worked. If it was in fact 2k ohms, then that would account for your no-start, and jumping the interlock should allow the engine to run. If your meter is autoranging, then you would want to pay close attention to what it is actually telling you. You would still want to do the jumper test.

 

[85MR2RED]

Thanks for the response. I did read the CEL and there were no stored faults. All of my figures are ohms not K ohms (I should have been clearer on that). I am going to do the test you suggested today and I will report back what happens. Thanks again.

 

[85MR2RED]

I conducted the test however the results were the same, the engine will start rev to about 1600 RPM and then die. It will do this twice then on the third attempt will get to maybe 800 RPM then die. At this point will not fire (will crank).

I got to wondering if maybe the injectors were stuck so I removed them, cleaned them as best as I could and then reinstalled them. They all worked (although a couple seemed a little weak) and I shot carb cleaner through them and they did flow. I have not yet tried to start the car again but I think I will get the same result. The fuel rail had fuel although it didn't seem to have a lot of pressure which seemed odd. I am still waiting on my banjo adapter for my fuel pressure test gauge so I don't know what is going on there. I guess my main point is that fuel is flowing to one degree or another.

So I an basically in the same place at this point.

 

[salineselin]

I'm having a hard time deducing the behavior based on description alone. Could you take a video and post it?

 

[85MR2RED]

I will give that a try however its pretty straight forward, starts then dies pretty much in the same time as it takes to read what I just wrote.

In my mind I am think that either the fuel pump is not producing enough pressure or there is some electrical related issue. I cannot determine the fuel pressure issue until I get the adapter and I am not familiar enough with these cars to diagnose what if any electrical issue could be present. To me the electrical side seems like a distant possibility because it does start, so it comes back to fuel.

Unfortunately I am a "one man band" so I cannot try and start it and video anything other than the instrument cluster.

 

[85MR2RED]

UPDATE... It now runs.. I am not entirely sure what was going one but I received the adapter so I could check the fuel pressure and had my son attempt to start the car, when he did it took off and ran. I kept it running until I got it operating temp, fuel pressure remained steady at around 31 psi or so. The engine stumbled a few times but then cleaned up. Now I just need to put it all back together, put some new tires on it and see how it drives.

I do a couple of questions

1. The brake light stays on, the hand brake is depressing the switch and the switch is connected.

2. Anyone know what this plug is for? I cannot find a corresponding connector. I do have the interior out of the car but I cannot find anything that connects to it (maybe I just missed it). It is in the same loom as the fuel sending wires.

 

[rmeller]

... It now runs.. I am not entirely sure what was going on...

...The brake light stays on, the hand brake is depressing the switch and the switch is connected...

That sounds like a bad electrical connection. If so, it is likely to keep recurring until you find it.

Low brake fluid. If the fluid is in fact high enough to lift the float then it is a bad switch, either in the fluid reservoir or under the handbrake.

 

[85MR2RED]

Thanks for the reply. It very well could be an electrical issue but it seems a bit coincidental that it started after pulling and cleaning out the injectors.

 

[rmeller]

It could in fact be the injector connectors that were loose. The 85-86 cars had injector connectors with latches that were really fragile, and they would break if you looked at them crosseyed. The connectors worked fine without the latches, but they could back out over time, and that would give you a cylinder that did not fire. If the engine started stuttering, then I would get out and push the connector back on.

 

[85MR2RED]

Yeah that could certainly be part of the problem. I know that one injector was plugged maybe not completely but significantly but I suspect at least one if not 2 others were the same. So perhaps a combination of plugged/gummed up injectors and the connections was causing me this issue. Starts right up and idles now (knock on wood). Now I need to put the rest of it back together.

I am still trying to figure out what that plug/connector is for down by the fuel sending unit.