I've got a '94 Ranger with a 4.0. The fuel pump occasionally doesn't come on (no sound) and engine won't start. If I wait 30 minutes, it starts. How can I test the fuel pump? What else could it be? It happens whether engine is hot or cold.

 

does it run fine after you wait 30 minutes? It may be the relay associated with the fuel pump.

 

Welcome to FTE!!!

You could pull the connection at the inertia switch and apply 12v there, bk/pk wire on my 1989 diagram, to see if it runs rather than getting under the truck but if its a wiring problem it may give you a false result. It sounds more like one of the relays is hanging. The next thing I would try when its not working is to ground the fuel pump test lead at the eec-iv test connector, tan/lg wire on my 1989 diagram. If it runs then it might be an EUC problem, if it doesn't then I would check the relays. If your familar with testing circuits with a meter I can email you the diagram.

 

I replaced the relay once, but the problem came back. One time when it worldn't start, I took out the relay and plugged it back in, and it started. I tried this trick on another occasion, and it didn't work.

 

I would deterime if your getting power to the inertia switch, then you can work in that direction to find the open.

 

I had the same problem, you could have gotten a bad relay. They are cheap, I'd get another just to make sure. There are tests that can be done on the one you have now, but buy another and be done with it.

 

Excuse my english because I speak french (Quebec).

I had two problems with my 1994 mazda B4000 (one similar to yours):

First) My EGR system worked bad.

Second) When I put my ignition switch to "run", sometimes, I did not hear my fuel pump making any noise. My truck cranked but did not start. When I did hear the pump, it started. The problem was growing; at the end, it was an everyday problem.

1) I checked and changed the relays (EEC and fuel pump). It changed nothing to my problem. The diode was OK. Inertia switch was Ok. Ignition switch OK. Fuel pump 1 year old.

2) I noted that when my truck was in "trouble", I did no see the the "check engine" light appear on my dash (like batterie light, belt light...) before trying to start it (key in, ignition switch on)... It cranked, I had fire but won't start. Fuel pump does not work. No check engine light.

3) I noted that when I put my key in and turn my ignition switch to "on" or "run" (without trying to crank) and wait several minutes, my check engine light sometimes appeared on the dash (normal) and sometimes disappeared (not normal). When it appeared, I heard the fuel pump working well...

4) I noted that my trouble NEVER happened when I drove... So my Fuel pump works well...

5) I asked an expert to verify my PCM (power control module). He told me he was very good. He told me that something makes my computer working wrong. Something sending a "bad" message to my PCM. Probably a bad ground or something like that.

4) I verified all my sensors linked to my computer and found that the DPFE sensor had an electric problem. It was rusted and in bad condition. I removed it and changed it. Just by removing it, it solved my problem (very easy to remove... about 5 minutes). My truck started well four days in a row. I put a new sensor because without this sensor, my EGR system did not work and my check engine light was always on when driving.

Since I have this new sensor, my PCM works well and my truck always start well. My EGR "problem" does not exist anymore. I had no problem since the last 10 days. I'll tell you if the trouble appears again... but I'm sure it will not.

 

Thanks so much for your response. I'm going to check my truck for the same condition. Thank you for taking the time to give me so much detail. You may have saved me a lot of work! Your English is better than you think it is!

 

I am having the same issue with the fuel pump. But I am also having a problem with the silonoid switch on the firewall underneath the hood. I have replaced it twice and it is not clicking again when I try to crank the truck. (I hear a lound clicking noise come from it when I try to start.) It will eventually crank but I am wondering if the problems are related. (Electrical)