raywu729

Hey. Does anyone have problems re-starting their fd after its been warmed up? Sometimes (especially in the summer) I have to pump the gas pedal for it to restart. However, it doesn't always work and I'm afraid to pump too much gas because it might cause flooding? I did some research and some people say its because of the ecu, but I'm not sure. Thanks in advance.

Additional Info: 1993 Rx7. Idle is 750 rpm and no major mods (just Apexi intake and exhaust) but I experienced the same restarting problem even before these mods.

1QWIK7

iTrader: (33)

Have you compression test your engine before?

raywu729

No. But my mechanic said the compression should be fine. She runs fine and idles perfectly. Its just really hard to start when hot.

OneRotor

iTrader: (3)

Normal symptom of low compression is hard hot starts. Buy yourself a compression tester and check your compression. It's not hard, and you won't be taking someone's word for it.

1QWIK7

iTrader: (33)

Yup, i would do a compression test to be safe. Then you can eliminate that and diagnose something else.

DaveW

I'm not sure what pumping the throttle pedal woud do to help restarting. This is not a carbureted car where "pumping" the pedal actually added gas by working the accelerator pump (which fuel-injected cars don't have).

Hard starting hot is a classic symptom of low compression due to wear. Even the 1st-gen RX7's had that problem. They never ran badly, but they would wear to the point where they couldn't be started, and hot starts were the worst.

IRPerformance

iTrader: (41)

Low compression, leaking fuel injectors, or a weak coil are common symptoms. I would get a proper compression test done.

96fd3s

i always thought pumping the throttle allowed more air into the engine - which in turn helps it to burn excess fuel thats in the combustion chamber - almost like a choke. Hence why pumping the throttle can help get a flooded engine started.

thewird

iTrader: (8)

What spark plugs are you using?

thewird

GoodfellaFD3S

iTrader: (213)

Who is your mechanic?

Original motor? mileage? Vacuum at idle?

I'm betting low compression based on the info you've given so far.

raywu729

Mechanic: Idk my dad has a shop so has like a lot. Basically all off them have worked on the car. In case your wondering about their skill they have done a lot of engine rebuilds (Sti, cobalt ss...) and etc.
Mileage: 107059
Vacuum at Idle: No idea but she should be fine.
The thing that bothers me is that she's restarts fine except only when really really hot. If I just start her and leave her running/warming up for about 5 mins and shut her off she's easy to restart. However, if the engine is hot and fans from the radiator are running after revving just to increease temp so I can test if she is hard to restart she fail the test. I'd have to pump gas to make her restart.

IRPerformance

iTrader: (41)

You can't assume the compression is fine just because the car starts. Compression will be higher when cold and can drop enough once the car warms up to cause difficult starting. You need to get it tested with a rotary-specific tester.

DaveW

The combination of low compression due to wear, (possibly) slower cranking, and looser clearances when hot MAY make the peak compression pressure low enough to cause this. Get a compression check to confirm whether or not low compression is the cause.

djseven

iTrader: (56)

Im betting on low compression also. With that mileage on the car it is highly likely rebuild time, if that is the original engine be glad it made it that long.

GoodfellaFD3S

iTrader: (213)

As stated above, based on the mileage the compression is most likely low. I'd consider yourself fortunate, that's on the absolute high side of mileage in FDs.

1QWIK7

iTrader: (33)

I agree, do a compression test ASAP because if the engine is done, i would rebuild it right now because at least now you can most likely reuse some parts, saving you money. If you want til something breaks, you will have to replace parts.

Just think of it this way, the longer you wait, the more money you'll end up spending later on.

Just be safe and do a compression test. And if it comes out no good, do rebuild NOW..

You have great mechanics who have given you advice in this thread, and they are local too. Please take their advice.

Dudemaaanownsanrx7

iTrader: (23)

I agree also with it being low compression.

To the response of chokes....Chokes block off air to increase the amount of fuel or richness when an engine is cold, not reduce fuel or increase air. So it's actually the opposite. Older cars used to be pedal pumped to squirt fuel into the engine, especially when cold. As mentioned the rx7 is fuel injected and doesn't squirt fuel with the pedal. It's just as well though cause it would make it even harder to hot start. But, If the pedal is pressed all the way to the floor it will trigger the injectors not to fire during cranking which may help with a low compression engine and hot starts.

Something else that can be done as a band aid, is hook a switch up to the fuel pump and shut it while hot cranking then flip it back on as the engine fires. Low compression engines just don't like much fuel when their hot.

raywu729

K. I'll try to get a compression test asap.