Hard cold and harder warm starts solved


Sep 4, 2002
Kansas City
I have a rather long winded story about a hard start problem on my 2002 Jetta. Several years back, when I hot rodded my Jetta, I bought an 11mm injection pump for $100 from a forum member who said in his ad that the salvage yard cut the connector and he thought it was probably unusable. When I pulled it out of the box to see if I could rewire it, I was pleasantly surprised to see the salvage yard had cut the wires before the connector for the IP so it was perfectly fine. :)

I installed the pump after a preventive reseal and ran it hard for 200k miles.

Fast forward to this past winter, I was traveling for work and ended up in Milwaukee and Peoria on days when the temp was 20 below F with wind chills in the -30's and had some very long crank starts. I do carry an extension cord, but neither hotel I stayed in those days had a place for me to plug in :(

After spring hit, I noticed some longer crank times when cold, and progressively worse long crank times when hot. 5-6 seconds cold and 10-15 seconds hot. No DTC's were set and the car ran perfectly once started. I have actually been getting 50-56 mpg on every tank since my new low rolling resistance tires were installed and the car seemed to have decent power.

I did notice a feeling during hard acceleration that felt like worn inner CV joints, figured they were probably coming due soon.

I decided to dig into my hard start problem while at the shop today, I started by checking compression, close to 500 on all 4. Verified proper cranking RPM with VCDS. Verified relay 109 was functioning properly. I then removed the case pressure relief valve, and sure enough it had come apart completely. I put it back together and still had hard starts :( I checked fuel flow with a spare injector and during cranking I couldn't see any fuel flowing until the car started sputtering to a start after the usual 15 second warm start cranking.


Case pressure must be too low from excessive wear from the sub 20 degree starts. Earlier the summer, my daughter's Golf was due for injectors, and she isn't a power junkie, so when I installed the Sprint 520's in her car I also swapped her 11mm injection pump with a 10mm pump I resealed so she wouldn't notice any power increase. (Her car came with an 01m but is now sporting an 02J) I saved her pump for a rainy day.

After installing the spare 11mm pump and priming and bleeding injectors, the car started like it used to, nearly immediately. Cold or hot, it busts right off. And my acceleration vibration is gone, so I'll be getting more miles from my inner CV joints.

I thought I would share this in case it will help anyone in the future.


Gadget Guy
Sep 29, 2003
Springfield VA
... None :S
As pumps age their output pressure gets worse and worse due to internal leaks (just like an engine). I noticed the same thing when I replaced the pump on my 99.5 TDI at 280,000 miles... the car starts better, runs better, smokes less, and the turbo boost control works better!



Veteran Member
Sep 19, 2008
2003 Jetta
I have had about the same experience. I was having hard hot starting problems. It went from about 10 seconds to around 20. It would start easy when the engine was cold. IE several hours not running or after sitting all night.

It had 440,000 on it. Its an automatic with the original tranny.

With that many miles and being an 01M, I replaced the starter with a Bosh reman. That did not help. Replaced the coolant temp sensor. That did not help.

I bit the bullet and bought a Bosh reman 11mm injector pump. It starts in 1sec and runs like a new car. What a big difference. Just like anything else thats mechanical parts wear out.
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Top Post Dawg
Apr 4, 2005
Stafford,NY (WNY)
'03 Galactic Blue Jetta TDI, '15 Silk Blue Golf Sportwagen TDI
So maybe my car is due for a pump(391k now). Abacus resealed it last month,but we couldn't get the case pressure valve off-so that's an unknown. I haven't attempted at removing it,cuz with my luck I'll break it,then I'd be screwed.


Veteran Member
May 20, 2006
Western NY
99.5 Jetta, (2) 02 Jetta, 03 Jetta, 15 Jetta
Dogdots I had a similar problem with a new pump on a new 03. Dealer couldn't solve it. Car ran fine warm and I bump started it for years. One day the IP went toes up. No flow at all when cranking. FWIW.