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Transmission and Starting Problems

My truck has difficulty starting after sitting overnight but runs perfectly fine after starting. If the truck only sits for a couple of hours it will start right up as well. What could be the problem? My truck also has a transmission issue where the automatic transmission slips really badly when the truck exceeds 3500 RPM. Do you think the two issues are related?

Any thoughts would be much apreciated.



I doubt if they are related. That overnight issue sounds like it may be a fuel pump problem or a fuel line problem.

For the transmission issue, I would wait for Transman to show up.

I was thinking it might be a fuel pump as well (back check valve), but could it also be a pressure regulator or injectors?

You’re going to need to be a little more specific. First of all what year is your truck? Second, when do you notice the slipping? When starting from stop? when cruising at highway speed? can you tell what gear your transmission is in when it starts slipping? How fast are you going when you notice the slipping?? As far as the hard starting, what exactly happens? Does it crank for an extended time before finally starting? Does the engine even crank at all? What I am getting at is it could be related if the engine wont crank and the transmission loses power due to a faulty ignition switch. When the transmission loses 12v it defaults to 3rd gear. Trying to take off in 3rd gear could make you think the transmission is slipping because the torque is not there. Another thing is that ignition switches in those trucks were known to be bad.


The truck is a '96 with I believe the 4L60e transmission. The slipping occurs in pretty much every gear but is most noticeable at highway speeds when trying to overtake another vehicle. I feel it in lower gears mostly as the vehicle shifts. The trucks acceleration lacks as the RPMs increase and then when the shift occurs the truck accelerates a lot more. At highway speed it is very noticeable when it shifts into third and revs really high, but doesn’t accelerate. If you let off the gas a bit so that it shift back into fourth it immediately bites in as the RPMs reduce. I haven’t tried going fast enough in fourth >90mph to see if it indeed does slip in fourth as well. I am also sure the vehicle is shifting properly 1-2-3-4-OD.

With the hard starting problem, the truck turns without any problem but just take 6-10 tries before it finally starts. I have depressed the schraeder valve on the fuel rail after the truck has sat overnight and fuel will only dribble out, so I’m fairly certain that I am loosing fuel pressure over an extended period of time, I’m just not sure where.

Hope this info helps.


The truck now will not start at all. The engine cranks and every now and againe it will catch for half a second or so, but it never actually starts.

you may want to inspect your torque converter may not be torqued proper make sure trany bolts are tight… as far as not starting I would say pressure Valve not sure where located depends on motor

Can you find out whether you’re lacking fuel or spark? Its got to be one or the other. You can use starting fluid in the intake - if it fires at least briefly then you probably lack fuel. You can pull a plug or use a spare plug or a spark tester to check for spark.