Hello,

I have a 90' bronco, 5.8 liter. It starts fine when it hasn't been running for awhile. If I stop it after the engine is warmed up, and try to start it again it struggles to turn over. The harder the truck has been run, the harder it is to start, and the more the voltage dips when the starter is engaged. The other day I was running it hard through some backroads and when I turned it off I couldn't get it to start again. It just struggled like the battery was dead (it wasn't). I recently replaced my alt, and had the battery tested at the same time, so they are both fine. After the engine cooled down to ambient tempeture it started fine. I am wondering if this is my starter, or if it might be the solenoid on the starter. I've never heard any grinding or other bad noises coming from the starter motor itself, hence my suspicion of the solenoid. Or could it be something else?

On a related subject, why would a warm engine be harder to start than one at ambient tempature?

Cheers,
Tim

 

could be a couple things. Make sure the battery cables both Pos/Neg are in great shape. if they are original i would recommend changing them out. the starter could be culprit. another possible item would be the TFI module thats mounted on the side of the dizzy. when this item gets hot it will sometimes cause a hard start issue.

how old is the starter?

 

ECT or ACT sensor that is stuck at a low temperature reading will also cause hard starts when the engine is warm. This condition will also rear its ugly head as a loss of fuel mileage. If you have seen a drop in efficiency along with this situation, you could have a sticking ECT or ACT sensor.

NOTE: This situation may or MAY NOT cause any fault Codes to be triggered during a KOEO or KOER test so you will have to troubleshoot them by taking resistance readings at various temperatures and compare those readings against what SHOULD be.

I've posted the ECT/ACT resistance chart too many times to think about. Run a quick search using them as the search criteria and you should be able to get a copy of the chart.

 

Just a clarification: when warm, it's not that the engine cranks over and over and fails to start; it's that the starter itself has trouble turning over at all, lugging down as if under a large load. Once it turns over once or twice though, the engine starts just fine.

Kemicalburns:

I'll check the cables out, but I don't think that's the problem here; my lights and accesories are normal, and when cold the engine starts readily. Thanks for pointing out the TFI however, I'll look into it. So, why would an overheated TFI module cause the starter to struggle; wouldn't it affect the ignition instead?

greystreak92:

Well, I don't think my milage has gotten any worse recently, but it's a little hard to compare because my normal trip to town and back is about 2.5 miles of dirt road (takes about an hour) and 15 miles of highway driving (30 minutes). Because I have to go so slow on the dirt road, I use alot more gas than a normal 20 miles trip would imply. Still, I'll look into the two sensors you mentioned, and maybe try pulling the codes just in case. I would repeat my question to Kemicalburns though: would the malfunction of either the ACT or ECT sensors cause the starter to struggle, or would it cause difficulty of ignition, like when the spark is bad or the engine isn't getting enough gas?

Thanks again for the help everybody.

 

With that kind of issue, I'd bet you have lost a winding in the starter itself. It won't completely kill the starter but will reduce its capacity to crank especially when hot. If you followed Kem's advice and double checked connections to everything starter-related and all is good, the next step would be to have the starter itself checked out.

 

I've had a similar problem with my 1993 Bronco. We replaced the temp sensor, the fuel pump, the fuel pump relay and the fuel filter and it still has the problem when the engine is warmed up. Starter cranks hard it just takes a second or two to fire. Ideas? Other threads to read?