Question about 1985 Mazda RX-7

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Hard start problem

Trouble starting 13b street ported, WEBER side draft carb. Has good coil spark on both lead and trail, 5 lbs fuel pressure, new wires, new plugs, new cap and rotor. cranks strong but does not fire easily.

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I had the same problem right after installing a 45 DCOE on a stock 12A. The problem was the carburetor was not properly tuned. To tune it, refer to "Weber Carburetors", by Pat Braden, from HP Books. The main thing I had to do was adjust the idle mixture screws. Seat them lightly (screw them all the way down, but not tightly), then turn both of them out 3 and a half turns. Pull the choke and turn the key WITHOUT pumping the gas pedal. You may also need to adjust the idle speed screw, I've found that about 900 or 1000 rpms is a good idle speed for my particular aplication, but when I first started it with the Weber, I had it at 1500 rpm. It took me about a week of driving it and adjusting it to different settings to get it to run well with a reasonable idle speed. Good luck!

Posted on Nov 01, 2008

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Why will my 1982 honda prelude start but wont stay started


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Sep 06, 2014 | Cars & Trucks

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Firing order 84 madza rx7


If your tach does not work that is a symptom. Of course a timing light is most useful. If not you can coil wires (swap with known good wire) ; check ignitor,(swap trail/lead ignitor plugs at distributor) coil, check with ohm meter.
Trailing ignitors are very common failures, especially when either jump starting or being jump started when a battery is stone dead. What happens is there can be a huge power spike through the ignition system damaging the electronics in the ignitor. 90% of trailing ignitor failures happen during a jump start procedure.
At this age though, wires and coils can be suspect. My recommendation for ignition parts, Mazda Mitsubishi Cap/rotor and NGK wires and plugs. They are good enough for Mazda factory race teams and I have been using them since 72 with no ignition related failures in racing or all the street vehicles that have been maintained. Most critical is the fit of the rotor, it should be very hard to install, very tight fit. If loose the rotors have a tendency to rotate and move causing changes in timing and at worse damaging the cap and rotor.

Apr 20, 2013 | 1984 Mazda RX-7

1 Answer

I'm not sure which sparkplug and coil wires go


OK most stock engines for daily street driving use the NGK BUR6 and BUR8 spark plugs the 6's go in the Leading side so the bottom 2 spark plug holes. The 8's go in the Trailing side which is the top 2 spark plug holes.

Now as far as the plug wires. You have 2 coil packs one will have markings by the output tips that say L1 and L2 the other will say T1 and T2. its very simple L= Leading side, or bottom plug. T=Trailing side or top plug. 1=Front rotor, 2=Rear rotor.

Hook up everything that way and you should have no more issues.

Jul 31, 2010 | 1987 Mazda RX-7

1 Answer

Started ran for awhile then died an wont start


Start with the simple and replace your fuel filter, a dirty filter can cause your engine from starting. At worst, your fuel pump has failed and will need to be replaced. Before replacing the fuel pump, inspect all the fuses and wire leads from the fuel pump harness. Note: that the ground wire is separately grounded at the frame, so inspect that for any damage due to corrosion.

You need 3 things.
Compression
Good hot blue spark to all plugs.
Good gasoline and proper fuel pressure. 63-64 lbs.
If you have all 3 then move on to injector pulse to all injectors. I think each injector is on a seperate driver on that one. Check for pulse to all of them.

You may be weak on fuel pressure, even a couple of lbs low on a cold start will cause a no start. Double check cold start cranking fuel pressure. If under 63-62 lbs you have problems. One test is to give it a squirt of carb cleaner not starting fluid. If it starts then you have a fuel pressure problem.
Run the full fuel pressure test, here is the guide lines on testing.
Hard to start cold.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure. Later V6 and V8 gm engines should have 60-66 fuel pressure.
* Cold start should be 64-65 lbs of pressure. If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
* Engine running should be 60-66 lbs pressure depending on engine load.
* Full pressure with return pinched off should be 75-85 or more. and if it has a fast leak down after shut off you have a leak.

The 75-85 is only a check on the capable full pressure of fuel pump. If you can not find the rubber return line check full pressure by plugging return line or just or the true full pressure can be taken direct at the end fuel filter.

Mar 18, 2010 | 1999 GMC Sierra

1 Answer

Will not start only backfires and start dieseling.5.7 automatic. hear fuel pump running. ran fine last trip and parked overnight. few times in past week or two. little trouble starting. rough idle for few...


You need 3 things.
Compression
Good hot blue spark to all plugs.
Good gasoline and proper fuel pressure. 63-64 lbs.
If you have all 3 then move on to injector pulse to all injectors.
I think each injector is on a separate driver on that one.
Check for pulse to all of them.

You may be weak on fuel pressure . Even a couple of lbs low on a cold start will cause a no start. Double check cold start cranking fuel pressure. If under 63-62 lbs you have problems.one test is to give it a squirt of carb cleaner not starting fluid. If you get a intake or engine full of starting fluid it can blow things. Carb cleaner will start it if it is a fuel problem and lot safer. Also in the good old days when i was a kid, i used to get a couple of cans of starting fluid and get in the back and have a good starting fluid spraying contest. Good for a big blast if someone lights a match. If it starts then you have a fuel pressure problem. Run the full fuel pressure test and post back pressures.

Here is the guide lines on testing.
Hard to start cold.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel. Do not leave home without it.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak.


The 75-85 is only a check on the capable full pressure of fuel pump.
If you can not find the rubber return line check full pressure by plugging return line or just or the true full pressure can be taken direct at the end fuel filter.
What are the pressure readings that you have done.
What are your cold start pressure readings?



Feb 01, 2010 | 1998 Chevrolet C1500

2 Answers

1997 chevy blazer getting fuel and spark but not starting, only backfiring through carb.


You need 3 things.
Compression
Good hot blue spark to all plugs.
Good gasoline and proper fuel pressure. 63-64 lbs.
If you have all 3 then move on to injector pulse to all injectors.
I think each injector is on a separate driver on that one.
Check for pulse to all of them.

You may be weak on fuel pressure . even a couple of lbs low on a cold start will cause a no start.
Double check cold start cranking fuel pressure. If under 63-62 lbs you have problems.
one test is to give it a squirt of carb cleaner not starting fluid. If it starts then you have a fuel pressure problem.
Run the full fuel pressure test and post back pressures.
Here is the guide lines on testing.
Hard to start cold.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel. Do not leave home without it.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak.


The 75-85 is only a check on the capable full pressure of fuel pump.
If you can not find the rubber return line check full pressure by plugging return line or just or the true full pressure can be taken direct at the end fuel filter.
What are the pressure readings that you have when done.
What are your cold start pressure readings?
Post back what you have. Good luck

Dec 24, 2009 | 1997 Chevrolet Blazer

1 Answer

Car wont start. Has spark, tried Carb Cleaner.


You may be weak on fuel pressure . even a couple of lbs low on a cold start will cause a no start.
Double check cold start cranking fuel pressure. If under 63-62 lbs you have problems.
one test is to give it a squirt of carb cleaner not starting fluid. If it starts then you have a fuel pressure problem.
Run the full fuel pressure test and post back pressures.
Here is the guide lines on testing.
Hard to start cold.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak.

The 75-85 is only a check on the capable full pressure of fuel pump.
If you can not find the rubber return line check full pressure by plugging return line or just or the true full pressure can be taken direct at the end fuel filter.
What are the pressure readings that you have done.
What are your cold start pressure readings?
Post back what you have. Good Luck

Dec 24, 2009 | 2002 Chevrolet Blazer

1 Answer

I have a Silverado 1500, 4.3 with 132,000 miles. After start, it runs fine, no signs of malfuntion. However it takes extended cranking to start. The fuel pump & filter was replaced 10,000 miles ago....


You need 3 things.
Compression
Good hot blue spark to all plugs.
Good gasoline and proper fuel pressure. 63-64 lbs.
If you have all 3 then move on to injector pulse to all injectors.

You may be weak on fuel pressure . even a couple of lbs low on a cold start will cause a no start. Double check cold start cranking fuel pressure. If under 63-62 lbs you have problems. One test is to give it a squirt of carb cleaner not starting fluid. If it starts then you have a fuel pressure problem. Run the full fuel pressure test and post back pressures. Here is the guide lines on testing.
Hard to start cold.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak.

Also you mentioned that you replaced the fuel pump, it's common for the $15.00 wire harness from the fuel pump to the frame will break and there is a bad connection till the wires heat up. You can try this trick, turn your ignition on for 30 seconds "engine not running" and then turn it off for for 5 seconds and then try to start. This will energize the fuel line if the fuel line check valve is bad which is a part of the fuel pump and will heat up the wire harness which will make a better connection and see if the engine starts easier. Regardless, inspect the wire harness for corrosion and the ground is good. Good luck and keep me posted.

Dec 15, 2009 | 2000 Chevrolet Silverado 1500

1 Answer

RX7 with 13b engine is hard to start, idles fine, dies on accel.


problem like this on garden tractor ,was weak coil ,-when engine at low manifold pressure[idle] spark could jump gap and fire cylinder ,higher pressure /under load-wouldn't fire...check color of spark -orange,yellow ,white spark=weak, blue spark is stronge,

Mar 22, 2009 | 1984 Mazda RX-7

1 Answer

1985 camaro that does not crank


Stop jumping all over the place!!! 1. check for spark. If none find out why. Check for proper timing. "basiline" timing at about 8 degrees btc. MSD units are nice when they work, but if no spark, pull it out and get an old style hei setup and stick it in there for a while.(hooks up with one hot lead) 2. If spark is working, check bowl levels on carb (I do this by attaching a syphon hose to fuel inlet and opening port on side of each bowl, adjusting level so fuel does not spill out and is just below level of hole.You checked the chain...is it in "straight up"? (cam mark down, crank mark up)
Fuel pressure should not be above 7.5 lbs. in fact, for start up testing I'd lower it a bit to about 5psi. (use a gauge) That way you won't be blowing needle valve off the seat. Unless you have the valves adjusted too tight, there is no reason for it not to start!!!
Good luck!

Mar 07, 2009 | 1985 Chevrolet Camaro

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