91 that won't start

[vasteves93]

I had the motor rebuilt a few years ago and I gave the car to my son. As long as you start the car every other day or so it's fine. But if you let it sit a week or so it won't start unless you pull start it. I have to get it up about 30mph in 2nd gear before it will start. We haven't tried to start for a couple of months now. Could it be losing fuel pressure some how? Sometimes when it starts it will smoke white smoke like its flooded. The battery is new so I know it's okay. The fuel filter is also new. Could the fuel pump be getting weak? Thanks for any help

[FerociousP]

White smoke is coolant.

jumper the yellow connector on the passenger firewall and hookup a pressure gauge inline with the fuel system (temporary)

[My5ABaby]

http://rotaryresurrection.com/2ndgen...l_failure.html

Try these.

1)
Remove your coolant fill cap, and fill the system up as high as possible. Leave the cap off. Remove your EGI fuse (or disable coils on the carb’d models) to prevent startup. Have an assistant crank the car with the throttle open for several seconds. Observe the open coolant hole for air bubbles or excess pressure pushing water out. Any pressure or air bubbles (consistent) observed indicate compression pressure being pushed into the coolant system past the seals, since the water pump is not spinning fast enough to do anything and there is no other explanation. Passing this test does not necessarily guarantee the lack of a seal failure, but it goes a long way in easing my mind. Failing this test pretty much guarantees a failure internally.

2)
Run the car to operating temperature, then shut it down. Refill coolant. Let sit overnight, or at least several hours. When you return, remove your EGI fuse/spark as described above. Get in and crank the car for just a second or 2, enough to amount to just a few revolutions. Stop, and go pull all of your sparkplugs. Any evidence of water/coolant on the plugs means it was pooled up at the bottom of the combustion chamber due to bad seals, and got sloshed up onto the plugs when you cranked it…failing this test guarantees a seal failure, but passing it does not necessarily exclude you from a seal failure.

[NoDOHC]

A couple things...

I have had coolant seals fail, it won't start after sitting for a few hours, the pressure has completely bled off by a couple days and the car will still start after a couple days.

After a while you will notice a loss of coolant too.

I am not ruling coolant seals out, but I wonder if it has the same issue my '91 has in the wintertime. If it sits for several weeks, it will always flood when you attempt to start it. It does not flood if you floor the gas before turning the key to start and then let up on it right away after the engine starts cranking. It works fine if the temperature is above about 20 degrees.

I don't know why it does this, but it does. It is fine after only a couple days or if it is warm out. I am not sure what causes this, but the symptoms are very familiar.

[vasteves93]

The smoke is like a RX7 will do when it starts after being flooded and it doesn't do it everytime. Could it be losing fuel pressure after it sits for awhile?

[tweiss3]

Originally Posted by NoDOHC

A couple things...

I have had coolant seals fail, it won't start after sitting for a few hours, the pressure has completely bled off by a couple days and the car will still start after a couple days.

After a while you will notice a loss of coolant too.

I am not ruling coolant seals out, but I wonder if it has the same issue my '91 has in the wintertime. If it sits for several weeks, it will always flood when you attempt to start it. It does not flood if you floor the gas before turning the key to start and then let up on it right away after the engine starts cranking. It works fine if the temperature is above about 20 degrees.

I don't know why it does this, but it does. It is fine after only a couple days or if it is warm out. I am not sure what causes this, but the symptoms are very familiar.

Mine does this all the time in the winter, 3 times a day when its cold out. No smoke or anything though, and pressure and fluids all are great so I never worried about it.

[My5ABaby]

Originally Posted by vasteves93

The smoke is like a RX7 will do when it starts after being flooded and it doesn't do it everytime. Could it be losing fuel pressure after it sits for awhile?

Any 7 loses fuel pressure after sitting for a while. However, the rails should pressurize pretty much immediately.

[RETed]

Originally Posted by FerociousP

White smoke is coolant.

Not necessarily...

Too much gas also will billow out white smoke.

There's a big difference in how each smoke smells though...


-Ted

[My5ABaby]

Originally Posted by RETed

Not necessarily...

Too much gas also will billow out white smoke.

There's a big difference in how each smoke smells though...


-Ted

If it smells like you want to lick your tailpipe, it's coolant. If it smells like a gas tank, it's gas.

[vasteves93]

I'm sure it's gas. What will make it start when you pull start it? I have to pull it a pretty good ways and get it up to around 30mph. It has started everytime doing this. After it starts it will restart fine as long as you don't let it set for more than a few days. It doesn't act like it's get gas at first. I guess I could try starting fluid but I'm kind of afraid of that with a rotor.

[My5ABaby]

Sounds like low compression.

http://rotaryresurrection.com/2ndgen...ion_check.html

Poor Man’s Compression test(free):
1) Remove lower sparkplug and wire from front rotor.

2) Remove EGI fuse from underhood fusebox to prevent fuel and spark while testing.

3) Have an assistant crank the car over for you, while you listen under the hood at the compression pulses coming from this plug hole. IT is recommended to put your hand/finger right in front of the hole to feel the pulses of air.

4) There should be one strong pulse/whoosh of air per full rotation of the crank pulley. Use the timing marks on it as a reference. There should be 3 even pulses in succession, without skips or gallops.

5) IF one or more pulses are weaker or non existant, this indicates (usually) at least one blown apex seal and severe internal damage. A full rebuild will be required, and no further troubleshooting will help.

6) IF this chamber passes the compression test, replace this plug and repeat for the rear. The rear rotor blows more often then the front on 88 and prior engines, and the front rotor blows more often on 89 and later engines, for reasons unknown.

7) With both lower plugs out at one time, you can listen/feel for compression on both rotors at once. This should be a rhythmic ch-ch-ch-ch-ch-ch sound, like an old steam engine train, alternating front to back, once per rotor per rotation. Any skips or galloping indicate loss of compression.

8) Note that this procedure can be used to test junkyard engines or engines out of the car. You will need a 19mm socket and ratchet to turn the front crank pulley bolt clockwise in quick, long strokes as possible to get a somewhat accurate reading. You will obviously not be able to turn the engine much at a time, so try to count each pulse as you go.


Compression test using a piston engine tester :
1) note battery strength. A weak battery will yield low compression results.

2) Remove both lower plugs and wires.

3) remove EGI fuse from engine fusebox.

4) have a friend floor the accelerator pedal, opening the throttle for more airflow

5) insert your tester into the leading hole

6) hold the valve on the side of the tester open

7) have your friend crank the car over for 5+ seconds.

8) observe the needle bounces. You should see 3 in succession without skips, even bounces, in roughly the 30-35psi range.

9) let out on the valve now, and let the tester reach an overall compression value for all 3 faces(highest of 3 will be displayed). 115+ is like new, 100-115 is healthy, 90-100 is getting weak(1 year or less in most cases) below 90 could blow at any moment.

10) repeat for opposite rotor. Note difference in overall compression between rotors, which should be no more than 20psi max.

[FRED]

Originally Posted by vasteves93

I'm sure it's gas. What will make it start when you pull start it? I have to pull it a pretty good ways and get it up to around 30mph. It has started everytime doing this. After it starts it will restart fine as long as you don't let it set for more than a few days. It doesn't act like it's get gas at first. I guess I could try starting fluid but I'm kind of afraid of that with a rotor.

To me that sounds like one or more leaking injectors. The fuel rail will stay pressurized over a half hour on a good system. IF one or more injectors is leaking it will cause flooding and or washing down of the rotor/housing.

There is nothing wrong using starter fluid. As long as you don't try to KEEP the engine running using it. Just one to three seconds into the air filter assy or snorkel will do. I'd suggest disabling the fuel pump when using it and I DON'T mean pulling EGI fuses bs when saying so. No spark if EGI are pulled. So spraying ether would do no good if you pulled fuses.

I never pull cars to start them. Ever.

As an aside I suggest checking and making sure the waterthermo sensor is connected up and or making sure it's contacts in the plug are not pushed back not making contact. Either that or making sure the ECU is seeing the signal from the waterthermo sensor. ECU uses the rpm, waterthermo sensor signal and seeing the START signal to deliver fuel when STARTING the engine. See training manual for what I mean. Lack of waterthermo sensor will not cause flooding though. So you might disregard that for now.

[vasteves93]

Thanks it might be next week before I can try and start it again.

[NoDOHC]

Originally Posted by FRED

To me that sounds like one or more leaking injectors. The fuel rail will stay pressurized over a half hour on a good system. IF one or more injectors is leaking it will cause flooding and or washing down of the rotor/housing.

A leaking injector makes the car stall at stoplights, idle erratically, stink very badly while driving and sometimes hesitate on throttle transitions.

After sitting for a few days, the rail pressure will have bled through the fuel pump and possibly the FPR. There is no more fuel pressure to leak into the engine and cause flooding. After 2 days, any gas that leaked in after shutoff through a leaking injector would long-since have evaporated.

If it were a leaking injector, hot restarts would be the worst by far (take this from a guy who has had leaking injectors).

Low compression also doesn't seem to relate to the problem. The compression will not change appreciable between 5 hours and 5 weeks, as it is mostly related to engine temperature. (Hot restart issues tend to crop up first with low compression).

What I found with my '91 is that leaving it on a battery charger will make it start much better than without, I wonder if this is because the cranking speed is lower with a partially-discharged battery - typically low cranking speed increases the chances of flooding.

[vasteves93]

I put a new battery in it about a year ago, but it has sit a lot since then. I might try to get over and see if we can get it started this week.