88GTU_AutoX

iTrader: (1)

To begin, I've searched...

I just finished my first rebuild in my 88 gtu, and I've been working to start it for three days now. It's got a mild streetport, new apex seals, springs, blah blah blah.

I have spark, the timing is approximately on, I have air, and, according to todays compression test, I have 90 in front and 85 in the rear on at least one face (normal compression tester) which sounds reasonable for a newly rebuilt engine. I've replaced the primary fuel rail with an s5 one due to a bad pulsation damper. I've been trying to start it while being jumped by another car, so it's cranking fast. I've injected oil to increase compression. I've tried starting fluid.

I have just one lead.

As far as I can tell, it's a fuel problem, and I think the injectors may be bad. I have yet to test the primaries, but that's next on my list.

However, it still could be a vacuum leak, or possibly the timing just isn't close enough.

At any rate, tell me your ideas, tips, and tricks, oh almighty rotary gods.


Thanks.

VANHALEN

iTrader: (3)

You sure you have the fuel lines correct ? In/ out
Jumper the yellow connector near the pass. shock and turn key to "on" (not start).
You should hear the fuel pump turn on and fuel lines pressurizing.
You don't need to have the UIM on to do so you can trace the problem. If you're not sure if it is priming, turn off the car and loosen one of the fuel lines . If no fuel, then there it is.
Or, it could just be flooded.

Injectors don't go bad just sitting a few weeks.

beefhole

iTrader: (29)

Yes, always check timing. Compression is LOW. After trying to start it, you probably flooded it. You need to de-flood, and try again. Worst case, push start it. It will get going.

satch

iTrader: (1)

So, the car will not start w/starter fluid?

88GTU_AutoX

iTrader: (1)

Alright. I'll try the unflooding again. I just don't try it very often. Tomorrow is probably going to be the day in which I resort to push starting.

Is 85-90 psi that low for a fresh engine? I was unaware...

Yes, I tried starter fluid, but the thing was just about empty, so I'll pick up another can tomorrow.

88GTU_AutoX

iTrader: (1)

Also, how can I accurately check timing when the engine won't run? I know how to line up the CAS and the pulley for a rough guesstimate, but a timing light doesn't work unless the engine is idling, right?

88GTU_AutoX

iTrader: (1)

Yes, I've done that. The shorting the connector trick. I do know that the lines are priming... But the soundthe engine makes when it's trying to start suggests that it's either running lean on fuel, compression is too low, or timing is off.

The starter is able to get the engine quick enough to start helping push itself along, until it just seems to hit a peak speed, similar to the way an electric motor acts when it reaches its redline. It makes me think that fuel could be too thin... I'm just spitballing here...

VANHALEN

iTrader: (3)

See if the spark plugs are soaked with fuel .
If it is , you need another set .
For timing , pull out the CAS , line up the marker on the front cover with leading mark . Take off CAS cover , check the marker on the lower CAS is aligned .
When you stab it back in , use a flat head on the gear so it doesn't jump too far . after starting you'll be a little off
so set timing with a gun .
Never had problem starting up .
If it sounds like its just turning over and not catching,
it may be flooded .
Pull out the EGI fuse crank for few seconds then
pop it back in and try again . If it sounds like its catching and not starting, it's flooded .
Starting a fresh low compression motor takes patience .
Having a battery charger helps too since you'll be cranking away .

88GTU_AutoX

iTrader: (1)

^^ The input is much appreciated. The plugs are brand new... they can't be fouled this quickly, right? I understand the need to dry them, but I don't think they're trashed.

I'll work on the timing and flooding tomorrow as well then.

VANHALEN

iTrader: (3)

It's not trashed if flooded but you can't re-use them so quickly. Good to have a spare set for times like this. You can try some brake clean if that's the only set you have.

edit: The part about just turning over and not catching is another issue...not flooded.

NativeBeggars

iTrader: (1)

Have you taken a look at the TPS yet? Before I rebuild my 89 like a 13BRE, I couldn't get my blown motor to start with everything good, even though I had it running before. But I set my TPS and despite having a totally blown rear rotor, it still fired right off. Do you still have the S4 unit or an S5?

88GTU_AutoX

iTrader: (1)

Alright. I'll pull the plugs and clean them...

NativeBeggars, I still have the s4 TPS, but I guess I never thought that it could be an issue... I really wish I owned a multimeter to check it with... :/

NativeBeggars

iTrader: (1)

Definitely get one. A must-have and very useful when owning an RX-7. See about having another member help you get it done with the multimeter in the meantime.

beefhole

iTrader: (29)

You can also pull the plugs, and put a small amount of oil in there. Then turn the engine slowly by hand. It should help a little with building compression.

I am not an advocate of starter fluid on a fresh rebuild. If you did it right, you don't need it. It's "cheap" but doesn't solve anything. Maybe on an old motor that sat for a long time, it's fine. I think it's a cop out though on something new.

JustJeff

iTrader: (13)

One thing I haven't seen is whether you checked to make sure you have your fuel lines correct. Priming the fuel pump will tell you if you have pressure, but you still won't get fuel if you have the actual fuel hoses reversed.

88GTU_AutoX

iTrader: (1)

^^^Lol. I did check. I had them wrong at the beginning, but I fixed that early. There is fuel in the lines.

rotornoob

iTrader: (2)

This may sound stupid, but did you verify that you are getting spark?

88GTU_AutoX

iTrader: (1)

Spark has been verified on all 4 plugs.

Right now, there has been no change in the starting, I've verified that the TPS is good (ohm-readings were close to perfect), I've unflooded the engine and brake cleanered the plugs... No change... :/

Looking at pulling the injectors just in case some debris got inside them from the rails or some such.

88GTU_AutoX

iTrader: (1)

Aright guys. I may be officially screwed. We went the push starting route. Engine started, then died due to low throttle. Once more, died..

The third time it started I drove it for 20 seconds, on premixed fuel, at about 3k rpm in first gear, because it wouldn't stay alive below that. It stopped for no reason in the middle of the street, skidding to a stop. I can't turn the crankshaft by hand (though I haven't put all of my weight on the bar), and I believe that it has seized. Help.

beefhole

iTrader: (29)

Make sure you're not in gear, and give it another go turning it by hand. You can do it with a large ratchet and 19mm socket easily by hand. If you have to put your weight on it, then yes you are screwed. You made a booboo when you rebuilt it. You're going to have to tear it down now and see what happened. None of us can know from our end of the computer screen.

g14novak

iTrader: (1)

Change the oil. If you spun a bearing, their will likely be shavings in the oil.

If you have no shavings in the oil, give this a try. Pull the EGI fuse and one of the leading plugs. Crank the engine and listen for the pulses of the engine. You should get 3 nice even chugs. If you get 1 strong chug and 2 weak, that could mean a broken apex seal. 2 strong chugs and 1 weak could mean a broken side seal.

The engine should turn fairly easily (especially with 85-90 compression) with a ratchet. If you have to put your weight on it, something's definitely wrong.

After a fresh rebuild, your looking for compression numbers of around 95-100. Then 115+ after the first 100 miles.

RotaryEvolution

iTrader: (30)

if the engine seized just pull it out, don't waste time trying to look at it from the outside.

rule of thumb: prime the engine before trying to start it. crank the engine with the EGI fuse out until the oil pressure comes just off of 0 while cranking. if the gauge does not move then you may have a lubrication issue.