Started engine, still won't accelerate?

ALLLEN

MEMBER
1994 MAZDA 626
4 CYL
FWD
MANUAL
145,000 MILES

94 mazda 2.0 engine 626 won't start. Got into vehicle. Started engine. Engine stalled when accelarated. Had to have vehicle towed home. Check of EGR valve showed rusted out. Replaced EGR valve. Started engine, still won't accelarate. Replaced distributor. Same problem. Vehicle being setting for two months. Now it won't start at all. More
Got into vehicle. Started engine. Engine stalled when accelarated. Had to have vehicle towed home. Check of EGR valve showed rusted out. Replaced EGR valve. Started engine, still won't accelarate. Replaced distributor. Same problem. Vehicle being setting for two months. Now it won't start at all. Fuel in line to injectors. Spark at plugs wire. Vehicle timing and belt checked ok. Connected jumper cables to battery to aid in starting. Engine spins to the point as if it is about to catch but no start. I have read about grounding problem or ECM bad. Any help will be appreciated. Vehicle engine ran great until this incident.

I sprayed WD-40 into the throttle body intake. Heard what sound like vacuum during the starting. It kicked but no start. The fuel pump will not run when ignition is turned on. So I jumped the fuel pump VIA diagnostic location. I checked for voltage at the injectors. There is voltage at each. I don't know what the voltage should be but it was the same at all of them. Fuel come out of the fuel regulator valve when I jumped the fuel pump.
Oct 05, 2009 - I changed the fuel regulator and checked fuel pump pressure by jumping at diagnois link. Gage showed 60 psi. The fuel pump will not run went ignition switch is turn on. It will only work by jumping. Fuel comes out of the return line when I disconect it. I changed ECM and throttle body purchased at junk yard. Still stumbles like it going to start but no start.

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Saturday, October 24th, 2009 AT 8:44 PM

19 Replies

KHLOW2008

MECHANIC
41,814 POSTS

Hi Allen,

Thank you for the donation.

WD-40 would not assist in starting. Starting fluid might help in diagnosing if it is the fuel.

To check if it is a fuel problem, you would need to test if the injectors are working to discharge the fuel while cranking. A noid lght would allow you to understand if the ECU is grounding the circuit to fire the injectors. The voltage at injector terminal should be battery voltage at one of the 2 wires with ignition ON.

One of the most common cause for difficult staerting would be the Air Flow Meter. Chek if it is secirely connected. Any vacumn leakages between the MAF and throttle body would cause the symptoms described. If there are major vacumn leakages, even if the engine can be started, it would stall when trying to accelerate.

The MAF is also responsible for fuel pump circuit while cranking the engine.

The fuel pressure is good at 60 psi. Did you test it by jumping the DLC or after cranking the engine?

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Sunday, October 25th, 2009 AT 3:53 AM

ALLLEN

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The WD-40 was used to clean old throttle body. I replaced it with a used one from salvage yard. I have sprayed gas in the throttle body with no results. Throttle body and MAF connections are tightly secured. I used noid light tocheck injector circuit. All connectors flashed when I tried starting. The fuel pump pressure was tested by jumping at DLC. The fuel pump will not run when ignition is turned on. I replaced the fuel pump relay. Still didn't work. I took cover off the old relay. When I jump the pump at the DLC. The contacts on the relay mates. I checked wirings at relay. A light green wire show no circuit or ohms, but when I jump at DLC, I get ohms. I traced the wire to under the dash. Checked for continuity from relay to under dash location. No reading. At further look at the Hayne Manual wiring diagram show wire going to DLC & ECU.

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Wednesday, October 28th, 2009 AT 7:37 PM

KHLOW2008

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WD-40 is not a good cleaner for throttle bodies. There are carb cleaners spray can that works much better.

From the additional info you have provided, the problem seems to be ignition rather than fuel.

Were the sparks at plugs bright blue or dull orange?

I would suggest getting a compresion test done to check the engine condition.

Do you have coolant losses or overheating issues?

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Thursday, October 29th, 2009 AT 1:03 PM

ALLLEN

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I checked the spark and the spark is close to yellow flame color. It is not bright blue. The distributor is a warranty rebuilt replacement. I had no coolant or overheating issues in the past. As I mentioned before, the vehicle ran fine up to the start and won't accelerate issue. You still did not address the problem of the fuel pump not energizing when the ignition is turned on. What effect does that circuit have on the starting? In my opinion jumping at the DLC may causing over fueling to the cylinders. I will check compression this weekend, time and weather permitting.

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Thursday, October 29th, 2009 AT 5:37 PM

KHLOW2008

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Sorry if I seem to be not addressing the fuel pump not priming during initial ignition on.

How did you come to the conclusion that the fuel pump is not priming?
Using the DLC to prime the fuel pump indicates no faults are present in the circuit opening relay circuit. I would suggest attaching a fuel pressure gage to monitor the fuel pressure at ignition ON.

Dull orange for the sparks means the ignition coil is weak and when this occurs, flooding would occur when engine is cranked for prolonged periods.

Weak sparks would also result in the inability to accelerate as the fuel cannot fully ignite.

A bad Air flow Meter

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Friday, October 30th, 2009 AT 11:20 AM

ALLLEN

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You ask, "How did I come to the conclusion that the fuel pump is not priming? In the information I have provided, I stated that the fuel pump does not energize when the ignition switch is turned on.

I do not heard the hum from the pump and a check of fuel pressure and disconnecting the line between
the rail and fuel filter shows no pressure or any fuel coming from the supply line to the rail with IGNITION ON. I also cranked the engine over. No fuel came from the fuel supply line.

As I continue to say, the pump only works by jumping at the DLC. I attached a fuel pressure gage to monitor the fuel pressure at ignition on. The pressue showed 50-60 psi. With ignition ON only by jumping at the DLC.

The question still remains, Why isn't the fuel pump energizing when ignition switch is turned on? Where is the disconnect that preventing the fuel from priming with ignition on?

You say a bad Air flow Meter. This is a pricey item with no return after purchasing. I do not want to buy a bunch of parts I can not return that doesn't fix the problem.

You mention the ignition coil weak. The coil is located within the distributor. As I also mentioned, I replaced the distributor twice since I have been having the problem. The distributor was replaced less than two weeks ago with a warranty rebuilt.

Will you please review all the information I submitted because it looks as if I am repeating the same symptons over and over to this problem.

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Friday, October 30th, 2009 AT 7:13 PM

KHLOW2008

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Sorry if I had caused any confusion.

The fuel pump is primed by the PCM at ignition ON and while cranking and since it is not priming, you would need to check the continuity between fuel pump relay or DLC and the PCM terminal 1H ( Light Green wire).

If coutinuity is good, the PCM would be the likely cause of the problem.

I don't trust rebuilts as I had my fair share of problems with them over the years of work so even if you had replaced a few, they can still be bad.

Check the PCM wiring and see if you can get any new info.

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Saturday, October 31st, 2009 AT 8:33 AM

ALLLEN

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I finally got around to performing some more work on the mazda. I performed a compression check on the engine. #1 Cylinder 90 -105 psi
#2 Cylinder 100- 110 psi
#3 Cylinder 100- 110 psi
#4 Cylinder 100- 110 psi

A contunity check of the light green wire from DLC and relay to PCM tested good. I sprayed starting fluid into the throttle body and the engine fired but did not start. It still seems to be a fuel delivery problem.

Do the light green wire control what routed to the starting circuit that prevent starting even with the fuel pump jumped at the DLC?

In your last post to me you mentioned the PCM as a proable cause. This is one of those non retrurnable item after purchase. There seems to be a ground or break in the fuel delivery system.

I followed the checks in the Haynes Manual for checking MAF. The checks are within the specificatons.

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Friday, November 13th, 2009 AT 10:16 PM

KHLOW2008

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The compression is below the minimum requirements of 119 psi. Try pumping some engine oil through the plug holes to increase the compression.

Disconnect the fuel injector and attach a noid light between the terminals. The noid light should blink while the engine is being cranked to indicate the PCM is grounding the circuit. If not, the PCM is faulty.

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Saturday, November 14th, 2009 AT 2:01 PM

ALLLEN

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It appears to me that you don't read all the post or the information I submit reference this problem.

The compression check performed using oil registered 120-125 psi. The compression check is on a cold engine that haven't started since May 09.

As I mentioned in one of my other post, I used a noid light to check the fuel injector circuit. Each injector harness flashed when cranking the engine.

As I keep saying, THE FUEL PUMP DOES NOT ENERGIZE when ignition switch is turned on or trying to start.

I asked about the light green wire. You mention continuity check. Those checks showed ok.

Is there a orund or break in a wire that preventing the fump pump from energizing? Are there any other sensor or fusable links that may be causing the problem?

I have known PCM being replaced but didn't fix the problem so I need to make sure all other components, sensor etc has been check before purchasing one.

If you will, please address my question and post sent.
Or can someone else chime in if they can help?

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Tuesday, November 17th, 2009 AT 7:36 PM

KHLOW2008

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Your post indicated a different reading from what you are referring to so I am confused why you are saying that I did not read your information.

I did mention that your test of using a jumper to prime the fuel pump works indicates that there is no ptoblem with the circuit and if the wire continuity to the PCM is ok, the PCM is bad but you refused to accept it.

Ok, I will get other technicians to have a look at this and hope they can come up with something, maybe it is something that I have missed out.

Hang on while I get the other technicnans to assist.

Sorry for not being to help as much as I would like to.

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Wednesday, November 18th, 2009 AT 7:33 AM

SERVICE WRITER

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Allen,

You have a very good guy trying to HELP you. No need to get porky with him.

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Wednesday, November 18th, 2009 AT 6:34 PM

ALLLEN

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Sunday, December 6th, 2009 AT 8:13 PM

ALLLEN

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I replaced the PCM. Fuel pump primes when starter is energized. Engine still will not start. Got a 9 code when checked code at DLC. A check of code show coolant temperature sensor or circuit. How is the temperature sensor checked? Will this prevent starting?

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Sunday, December 6th, 2009 AT 8:21 PM

KHLOW2008

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Yes, the ECT can cause difficult or non starting as the fuel metering is affected.

Here are the diagnostic procedures and schematic. They might not show up well due to the size and I will send another pdf copy to your email for you.

Since engine had been idle for a long period of time and the compression seems rather low, remove the spark plugs and squirt some engine oil into the cylinders via the spark plug holes. Crank the engine to get the compression up and reinstall the spark plugs to test.