I have a strange, and very annoying, problem with my Bronco that just recently started. When I get in and turn the key once it turns over fine. Usually doesn't start on the first try though because of cold weather here in Michigan, but it does turn over fine. However, when I turn the key a second time, nothing happens at all. All the lights come on fine, the fuel pump primes, everything acts as it should except the truck doesn't turn over at all. Not even a click.

Now, the odd part, I've discovered over the past few weeks that if I get out and open the hood then give the negative battery clamp a couple of sideways taps with a hammer that I can then get it to turn over again. Unfortunately, it seems I have to do this almost every time I turn the truck off.

Now, I know the immediate thought is that the battery clamp is loose or the terminal is dirty, but that's not it. Not only is the clamp as tight as it will go, I've actually changed clamps about 4 times in the past few weeks, with everything from the least to the most expensive I could find. No difference. The battery itself is brand new and I still cleaned the twerminals anyway. No help there either.

My next step will probably be to change the wires themselves, but I just feel like there may be a short or a bad ground somewhere that I can't seem to find.

Tested the alternator and it's fine. Solenoid is pretty new. Could be the starter maybe, but not sure how tapping the battery clamp would make it suddenly work every time. It just seems like it has to be a loose connection.. but It isn't.

Also, checked codes and nothing comes up.

Any thoughts? I would appreciate any and all help. Thanks.

C.

 

Replace the ground cable with a new one. Hit the contact area with wire brush to expose good metal for contact.

 

Ditto to NWBronco's comment. I had a negative cable corrode from the inside out one time. Took it out of the truck and dumped white scale out of the cable jacket til there was nothing but a small strand of wire about the size of telephone wire left in the jacket.

 

i had repalced mine and added a few more ground for assurance Good luck TR

 

Same thing here on my 85. I had a few problems (hard to start, weak window motors, would burn up coils. etc) my ground cable did the same thing, corroded from the inside out. I had a battery with both top and side posts so I ran one cable to the frame and one to the engine block. It made a huge difference, no more weak starts, windows and headlights are much stronger, cleaner burn on the engine and no more burnt coils. let us know what you find.

 

Well, I'm still working on the problem. I changed out my ground wires and even added a few extra to make sure I had a good ground and I seem to. But while I was doing all that I ended up burning out my ignition coil so I need to replace that before I can start working on the original problem again. (( Was an original coil on a 1990 Bronco so I'm surprised it lasted as long as it did. hehe ))

The original problem was still there after initially changing the wires though. I'm wondering now if the problem may be in the steering column itself...? I had an upper actuator break on me once and it was a pain to try to replace so I just ended up replacing the whole steering column instead. It almost seems like it could be that same type of problem starting again. Even when the truck does turn over I have to turn the key much further than normal and then turn it back into resting position myself.

The truck seems to turn over fine when I use a screwdriver to jump it off the solenoid. Someone suggested maybe I should just wire up a push button start to bypass the regular key start but I'm not sure if that's a good way to go or not. To be honest, I would hate to have to change out the steering column again.

Anyway, any thoughts on this would be appreciated.

Also, does anyone know where I can find detailed instructions, possibly with pictures, of how best to remove an egr valve and clean it? I think that may be what is causing my truck to lose power and not want to go on the rare occasions I can get it started. Fuel pump seems to be fine and the codes I got pointed to either that or the egr valve/sensor. Is there a way to test the sensor to see if it needs to be replaced without just buying a new one?

Anyway, thanks for your time.

C.

 

I've done a lot of searches about this and so far sentiment seems to be split. How do you guys feel about simply using a EGR Valve Block Off Plate to bypass it completely? Will it cause damage to the engine? Some say it will and some say it won't. Is it even safe to do on an older truck like mine? 1990 Bronco with a 302. Kind of torn because my truck just doesn't want to go, and the fuel pump checked out fine. The codes point to the EGR and a few friends mentioned I should just block it off, but I'm afraid it may cause more serious problems later on somehow.

I welcome all thoughts and opinions on this. Thank you.

 

Don't block off the EGR. It will NEVER run right. The PCM is "looking" for that information and if it does not get it, it will mess with your fuel/air ratio and timing terribly. Which codes did you actually get? If you have a vacuum pump you can open and close the EGR valve a few times by applying and releasing vacuum at the barb on the valve. This often clears whatever crud may be keeping it from moving. If you do this and the problem persists or you get the same codes again replacement is the remaining option. However, if I know WHICH codes you are getting we can pinpoint it further.

 

My apologies. For some reason I left out the codes that I got and I thought I had listed them. Blanked out there for a moment, I guess. Sorry about that. These are the only codes that I get every time I check:

Code 33: EGR valve opening not detected.

Code 87: Fuel pump primary circuit failure. When the FP relay was activated by the EEC, voltage was not detected on the control circuit.

Truck seems to be getting fuel just fine, so I feel like it must be the EGR. Also, I don't have a vacuum pump like you mentioned, but I'll definitely try to get my hands on one.

Thanks.

 

Code 33... typically a clever disguise for a vacuum leak. If 33 was pulled from continuous memory the condition happened the last time the vehicle was driven. If it was pulled from the KOER test, the condition still exists.

Make absolutely certain the EGR valve is getting vacuum. The vacuum pump will be helpful here because you can apply 2-3 inches of mercury and be certain that the valve is either functioning properly and holds that vacuum or it is trashed because it does not. If it DOES hold vacuum, clear the stored codes, run the KOER test and apply the vacuum yourself rather than letting the system do it. If code 33 does not occur, check the vacuum supply all the way back to the EVR (EGR Valve Regulator) solenoid. This solenoid controls the flow of vacuum TO the EGR valve. make certain there is vacuum present in front of the EVR and that it is allowing that vacuum to flow through itself in some degree (It can't control vacuum if it isn't getting any to control).

If you get code 33 even when applying vacuum to the EGR valve yourself, your problem is the EVP sensor. Check the electrical connections to it first. If they are intact at this point, you could get into checking the EVP sensor signal return at pin 27 of the PCM but having done all of the above, process of elimination would leave it as the ONLY culprit and therefore no check would be needed merely replacement.

I would caution you to check the FP circuit carefully since a "no start" condition is more indicative of one third of the ignition trilogy being absent. EGR problems will cause poor drivability and performance issues but rarely keep the truck from starting all together.

Code 87 is much simpler to troubleshoot. Start by making sure the inertia switch has not been tripped. (Up under the dash near the e-brake ratcheting mechanism). Just push the red plunger down to be sure its not tripped. Once you are certain of that check for battery voltage (approx. +12VDC) at both sides of the switch wiring. If you have battery voltage but still no start, check that you have less than 5 ohms resistance between pin 22 of the PCM and the fuel pump relay (wire color at the PCM should be the same at the FP relay). If the resistance does not exceed 5 ohms, replace the fuel pump relay. If that doesn't fix it, you are into larger issues like a dead PCM.

 

Well, I replaced my ground wire and cleaned up all the connections I could find with a wire brush and I seem to be getting it to turn over every time now. However, turning over apparently doesn't help when you have no spark at all. As soon as I fix one problem, another pops up. I adjusted the timing to see if that would help it run any smoother and then turned the truck off. Now it won't start again. It will crank every time, but there seems to be no spark at all. A friend tested everything for me and the problem seemed to be the ignition coil, so I put on a brand new one, but it still isn't getting spark. Plugs and wires themselves are pretty new and seem to test fine. Cap and rotor are pretty new as well. No codes at all for this problem. Not sure where to look next for the cause.

 

Try replacing the ingition control module.

 

Replace or rebuild distributor, it might be the stator in distributor, or the pickup module in the distributor. I had to rebuild my distributor after trying for 5 day to troubleshoot the problem using a Haynes manual. Finally broke down and took the distributor apart and put it back together again. Along with a new ICM (Gray). Oh, and a new coil that I didn't need anyway.