CB7 Difficulty Starting Sometimes

[AmTeC]

So I've had this CB7 since November of 2016, and since I've got it, its always started up almost as soon as you turn the key, provided that I prime the fuel system for a few seconds if the car has been sitting for 10 hours+. So in all this time I've had this CB7, it had difficulty starting 3 times, Once was in January, My dad has a habit of running the tank almost completely empty, so he went to the gas station and filled it up and brought it back, after 5 minutes I needed to move it somewhere else, and when I went to start it, she started right up, and then stalled, the then I tried to restart it, lots of cranking, and the whole time it was cranking it was kicking over like it was about to start but doesnt quite have enough fuel, it started and stalled a few more times before it finally started and STAYED running, once running it runs fine, no hiccups. It did this another time after filling up at the gas station from almost empty, just finished filling up and she wouldnt start for a good minute or 45 seconds. And finally yesterday, She has half a tank, I warmed her up for 5 minutes and then moved her out of the garage and stopped the engine, Then after another 5 minutes I tried to restart her and she refused once again, and again, after I got her running, she was smooth and gave no problems, an hour later she started right up as soon as I turned the key. It rarely does this but I wanna know whats causing it, ignoring symptoms is never a good idea.

[F22Chris]

This is starting to be a trend it seems. Check the basic things first, like ground and power wires with secure terminals on the battery.

It sounds like it's not getting enough fuel or air. Does it help to step on the throttle a bit? If it does help, check everything that allows/controls air entering the engine i.e. - air control valve, dirty throttle body, TPS, IAT sensor, and the coolant temperature sensor(though a part of the fuel system) as it's what controls fuel delivery when cold/open loop.

If that doesn't work check fuel pressure, and see if the regulator holds vacuum. Pressure should be in the mid 40's.

[cb7 calling]

This is common, I believe the fuel system floods but whatevs. Remove and replace the gas cap usually works, if not floor the pedal with the car off. This will help evaporate excess gas then start. This is not a solution though. I think the fuel pump relay going bad is the culprit.

[AmTeC]

This is common, I believe the fuel system floods but whatevs. Remove and replace the gas cap usually works, if not floor the pedal with the car off. This will help evaporate excess gas then start. This is not a solution though. I think the fuel pump relay going bad is the culprit.

That sounds about right to me, Every time its done this, it was just a hair below operating temp, or had just barley reached it. Someone told me that could be a flooding issue. If the fuel pump relay was going bad, wouldnt that cause the car to start hiccuping or stalling while its running?

[cb7 calling]

I've had two cb's do the same thing, what I found out eventually is I could hear the pump running with the car off before I had the starting issue. When I remove the gas cap the pump would shut off.

[deevergote]

I've never known CB7 fuel systems to flood. I suppose it's possible, but it's never been something that has come to my attention.
The fuel pump and fuel pump relay (also referred to as the main relay) are becoming more common problems as these cars age. The relay tends to fail when it gets hot, as the aged solder joints crack, causing the relay not to function. If the relay doesn't work, the fuel pump doesn't turn on. The solder joints can be repaired, or you can just purchase a new relay.

The fuel pump itself is cooled by the fuel in the tank. If allowed to run too low, the pump can get quite hot. Over time, this will kill the pump. 25 years of occasional overheating, and it's bound to go at some point. Of course, changing the fuel pump requires dropping the tank, which isn't exactly the most fun thing to do on a CB7 (especially if you live in an area where rust is common.) Replacing the tank, mounting hardware, and sometimes the fuel lines themselves isn't a bad idea if rust is an issue.

Before you dive into all that, though... you need to be absolutely certain you know what is causing your no-start condition. Your engine needs air, fuel, spark, and compression to run. Since it does run well eventually, air and compression are likely not an issue. That leaves spark and fuel. So far, it seems that a lack of fuel is assumed... but you should confirm it before you start taking things apart and replacing them. Although it does seem like it would be fuel related, fouled spark plugs could cause similar symptoms (and they're a hell of a lot easier to replace than a fuel pump!)

Finally, are you throwing any CEL codes? Does you CEL work? (check engine light, if you're not familiar with the acronym.)

[cb7 calling]

It's not flooding in the traditional sense of flooded but the pump runs with car off building pressure. As soon as the injectors fire it's too much fuel to ignite properly.

[F22Chris]

Can't argue with success. It makes sense, the main relay going bad maybe causing a short to power. Still odd that it stopped when the cap was removed.

I also read this wrong and thought the car didn't start. It sounds kind of like the line pressure is bled off, making bubbles in the fuel line. I'm still thinking CTS though.. Do you ever see black smoke from the exhaust?

[illinois_erik]

even the h22a swap does this, more common in the winter.
in and out, it wont start, you can try and try and try; sounds like its fucked.
wait 3 mins, fires right up like nothing..the F22 SE did the same thing except it
was worse..i just take it as a quirk of the chassis, dont use it for a heist..

[cb7 calling]

To be clear I'm not the op.....but honestly have replaced the relay and still found the same issue. Just listen for the pump and remove gas cap as needed. It's not your fuel pump.

[deevergote]

If that is indeed what it's doing, then something is wrong. That's definitely not normal behavior, and should be corrected before it does damage something.

[cb7 calling]

I've had two cb's do it for ten years.

[AmTeC]

I've never known CB7 fuel systems to flood. I suppose it's possible, but it's never been something that has come to my attention.
The fuel pump and fuel pump relay (also referred to as the main relay) are becoming more common problems as these cars age. The relay tends to fail when it gets hot, as the aged solder joints crack, causing the relay not to function. If the relay doesn't work, the fuel pump doesn't turn on. The solder joints can be repaired, or you can just purchase a new relay.

The fuel pump itself is cooled by the fuel in the tank. If allowed to run too low, the pump can get quite hot. Over time, this will kill the pump. 25 years of occasional overheating, and it's bound to go at some point. Of course, changing the fuel pump requires dropping the tank, which isn't exactly the most fun thing to do on a CB7 (especially if you live in an area where rust is common.) Replacing the tank, mounting hardware, and sometimes the fuel lines themselves isn't a bad idea if rust is an issue.

Before you dive into all that, though... you need to be absolutely certain you know what is causing your no-start condition. Your engine needs air, fuel, spark, and compression to run. Since it does run well eventually, air and compression are likely not an issue. That leaves spark and fuel. So far, it seems that a lack of fuel is assumed... but you should confirm it before you start taking things apart and replacing them. Although it does seem like it would be fuel related, fouled spark plugs could cause similar symptoms (and they're a hell of a lot easier to replace than a fuel pump!)

Finally, are you throwing any CEL codes? Does you CEL work? (check engine light, if you're not familiar with the acronym.)

The tank and its lines were replaced with new ones in december. The CEL works but its not on. Can there be codes even when the CEL is off?

[AmTeC]

I tried my very best to replicate this unusual behavior, I couldnt get it to happen again. She only acts up when she wants to ¯\_(ツ)_/¯
Its been daily driven since November 2016, and its only done this 3 times, all at quite different times, but all three times, the car had been restarted after just barley reaching operating temp. Twice after a short trip to the gas station, and once after warming up the engine and moving it out of the garage. The flooding thing sounds legit to me since the CEL is off and the plugs and wires are all new, as well the the dizzy. But I'm no expert.

[Tuage]

Yo i got my in september and same exact thing a few good months of bliss then random no starts...i ended up changing the starter, distributer along with cap and rotor. Which pretty much solved the problem only thing is i bought the starter from auto(death)zone which i heard there after was a huge mistake, i believ the pinion isnt kicking out far enough to grab fly wheel properly which causes a lot of failed turnover and gear grinding once it does catch, be careful where you get your parts as our cars are up to 25 years old and they no longer manufacture oem, the junkyard usually will have oem parts but keep in mind they will usually be about as old as the car...as long as your engine and trans are in good shape you should be ok but look forward to replacing components often unless you can get all new and throw them on at once...egr ports will most likely be noticeable pretty soon so watch out for that