My car won’t start. It tries to start more when you take out the fuel pump fuse or you disconnect the distributor and reconnect it. The first turn over after each of these is the strongest and the car almost starts. The turnovers after that do essentially nothing. The compression is between 40 and 75 on the cylinders on first test and around 75 on all four when tested with a little oil. Brand new spark plugs were installed today as well. I just want to make sure that I try everything before I think about whether I want to replace the engine or the car.
You need four conditions before an engine will start. These are fuel, air, spark, and compression. With the compression readings you’ve provided it would appear the engine lacks compression for it to start.
75 psi on the compression test? Wow, that is way low! How was it running last time it worked? Lots of oil burning?
It was fine. I think it’s because it got revved too high when it wasn’t warmed up. I don’t know if that gives you any clues as to what could have happened. I don’t know if something could have happened with the timing chain either. The only problem I was having before it got revved too high was that it loped a tiny bit out of a stop, for a second or so.
Are you taking the compression readings with the throttle held wide open?
If you aren’t, then that’s why your readings are so abnormally low.
I can’t keep the throttle open with the car only turning over, right?
Yes. Hold the accelerator to the floor as you turn the engine over, or, in the case of using a remote starter, physically hold it open with your hand.
I’m still trying to figure out what’s wrong with my car. I no longer have the compression tester. It was suggested that I test the fuel pressure at the Schrader valve on the fuel rail. Well, I pressed it with the key in OFF, ON, and starting positions and there was zero pressure at all. I pressed it down as far as I could and felt no resistance and saw/smelled no gasoline.
The person that suggested this also said that sometimes fuel pumps aren’t bad but the lines within the tank are. I always felt there was something with the fuel system before all this happened, but never confirmed it.
What I’m wondering now is how I could troubleshoot the fuel system without replacing every part. Can I disconnect different sections of the delivery lines and turn the car on or something and see where I stop getting fuel flow?
I’d appreciate any ideas anyone has. Thanks!
Fuel pump should be under the rear seat.
Take off the rear seat, and while someone turns the key from the OFF position to the ON position (not to the position that you crank the engine over at), you should listen to the fuel pump area, and see if you hear the pump making a whirring noise. That is the sound of the pump turning on for a couple of seconds.
When you crank the engine over, you should hear this sound the entire time the engine is cranking.
If you don’t hear the noise, then the fuel pump is either bad, or is not getting electricity.
To test to see if it is getting electricity, you would disconnect the fuel pump connector, and hook up a test light, or a Digital Volt Meter to the appropriate terminals of the car side of the connector. When you first switch to ON, or during cranking, you should get the light, or get a reading of 12 Volts at the connector at the correct terminals.
If you don’t hear the noise, but you are getting voltage, then its your fuel pump.
If you don’t get voltage, then you want to look at fuses, or the fuel pump relay.
You can also try jumpering the 12 V source for the fuel pump to see if you hear it run, and if the car can then fire up.
The fuel pump is getting power and is humming. I was hoping to be able to unhook something under the hood after the filter to see if it’s the filter and then before the filter to see if I’m getting fuel from the tank to eliminate an issue in the lines. My main concern is if there’s some kind of safety issue I’m not thinking of with disconnecting the lines to figure out if the problem is before or after the filter.
Thank you for the detailed description.
I’m still working on what you mean by saying that you “pressed it” while working on the fuel pressure. Are you saying that you’re pushing in the valve while someone is cranking the engine so that you can see if fuel shoots out? This is a really bad idea. Do you have an actual fuel pressure gauge? Don’t bother trying to figure out anything about fuel pressure without an actual gauge. You could get fuel squirting out - but will it be at exactly the pressure your fuel system needs? You need an actual gauge to know.
I mean no offense, but based on what I can gather or your compression “testing” (which there is still no clear answer about) and now fuel pump “testing” you either need to find a more experienced friend or just bite the bullet and get it towed to a shop.
In any case, there is little point in dwelling on the fuel filter. They are very cheap. If you have any question just replace it.
To pull apart sections of the fuel line the major safety item is to make sure all pressure is relieved - so just go ahead and wrap a rag around the Shrader valve and poke the valve stem for a few seconds. Then you can separate fuel line sections recognizing that gasoline will still come out - its just that it won’t spray out under pressure.
The compression test was done with a gauge, but - you know - when someone who is a mechanic offers to do something for you they’re not going to be happy if you start questioning their technique or knowledge (even if it is limited). I can get a gauge to check the fuel pressure, but what I’m saying is that there was no evidence of fuel period when I did the incorrect pressing of the Schrader valve.
The fuel pump is making noise, but I haven’t yet taken the seat off to check it.
My main thing is I want to narrow down causes before I hand it over to someone and let them charge me a limitless amount to figure out what’s wrong with the car. Plus, I am going to have to pay for a five mile tow if I want to get it to the closest reputable mechanic that I know.
Relieve the fuel system pressure - disconnect the fuel line before the filter. Hook up an appropriate sized hose to the fuel line and put the other end in a suitable container. Energize the pump. If there is still no fuel coming out, replace the pump. (All assuming that it is being energized.)